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Season 1

Unaired Pilot

Unaired
The very first pilot of The Big Bang Theory. Leonard and Sheldon make spending money by donating to a sperm bank and later meet an attractive young woman in distress, who they decide to help.
Uncredited: Amanda Walsh as Katie | Iris Bahr as Gilda | Vernee Watson-Johnson as Althea
Director: James Burrows
Songs: Thomas Dolby -- She Blinded Me With Science

1 :01x01 - Pilot

Sep/24/2007
Young scientists Sheldon Cooper and Leonard Hofstadter work at Cal Tech and lead quiet and uneventful (though nerdy) lives. Then a beautiful blonde aspiring actress named Penny moves into the apartment across the hall. She quickly changes things.
Guest Stars: Brian Patrick Wade as Kurt |
Uncredited: Vernee Watson-Johnson as Althea
Director: James Burrows
Songs: Mac Davis -- Baby Don't Get Hooked On Me

2 :01x02 - The Big Bran Hypothesis

Oct/01/2007
After bringing a package of furniture into Penny's apartment, Sheldon is appalled at the uncleanliness of the place so he sneaks inside one night to clean it. Needless to say, Penny is not thrilled.
Director: Mark Cendrowski

3 :01x03 - The Fuzzy Boots Corollary

Oct/08/2007
After Leonard sees Penny with a new guy he tries to trick her into going on a date with him.
Special Guest Stars: Sara Gilbert as Leslie Winkle |
Co-Guest Stars: Allen Nabors as Doug | Treisa Gary as Waitress |
Uncredited: Sherry Weston as Instructor
Director: Mark Cendrowski
Songs: Augustana -- Boston

4 :01x04 - The Luminous Fish Effect

Oct/15/2007
An argument with the new head of the Physics Department leaves Sheldon without a job. He then proceeds to drive the guys and Penny crazy with his antics so Leonard calls his mother in order to set his friend back on course.
Special Guest Stars: Laurie Metcalf as Mary Cooper |
Guest Stars: Mark Harelik as Dr. Eric Gablehauser |
Co-Guest Stars: Sierra Edwards as Summer
Director: Mark Cendrowski

5 :01x05 - The Hamburger Postulate

Oct/22/2007
Cello playing Leonard joins a music ensemble at the university which leads to a sexual encounter with fellow ensemble member Leslie Winkle. Sheldon, who despises Leslie, disapproves of this relationship.
Special Guest Stars: Sara Gilbert as Leslie Winkle
Songs: Bryan Adams -- Have You Ever Really Loved A Woman?

6 :01x06 - The Middle Earth Paradigm

Oct/29/2007
Penny invites the guys to a Halloween costume party at her apartment. Once there, Leonard gets into an argument with Penny's hulking ex-boyfriend.
Guest Stars: Brian Patrick Wade as Kurt | Rachel Cannon as Patty |
Co-Guest Stars: Erin Allin O'Reilly as Cheryl | Kimberly Kevon Williams as Vicki | Cynthia Holloway as Roberta
Director: Mark Cendrowski

7 :01x07 - The Dumpling Paradox

Nov/05/2007
Penny's slutty friend from Omaha, Christy, pays her a surprise visit and it doesn't take long for her to hook up with Howard Wolowitz. When Howard starts hanging out with Kristy it takes the others, especially Sheldon, time to adjust to his absence.
Guest Stars: Brooke D'Orsay as Christy Vanderbel | James Hong as Chen |
Co-Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Kimberly Moss as Automated Cell Phone Voice (as Kimberly D. Brooks)
Director: Mark Cendrowski

8 :01x08 - The Grasshopper Experiment

Nov/12/2007
Raj discovers that he can talk to members of the opposite sex after he's had a few drinks so he reluctantly heads out on a date arranged by his parents with a girl whom he knew in childhood.
Guest Stars: Sarayu Rao as Lalita Gupta | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Ted Wass
Songs: Sheldon Harnick -- To Life

9 :01x09 - The Cooper-Hofstadter Polarization

Mar/17/2008
Leonard and Sheldon's research paper is accepted for publication and Leonard wants to present it at a conference. Unfortunately, Sheldon wants no part of the presentation.
Co-Guest Stars: Talbott Lin as Chinese Leonard | Howard Chan as Chinese Sheldon
Director: Joel Murray
Songs: Richard Strauss -- Also sprach Zarathustra

10 :01x10 - The Loobenfeld Decay

Mar/24/2008
In order to cover up a lie he and Leonard told to Penny, Sheldon concocts an even more elaborate lie involving a fictitious drug addicted cousin.
Guest Stars: DJ Qualls as Toby Loobenfeld
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Bill Prady, Lee Aronsohn
Songs: (Unknown artist) -- Out Tonight

11 :01x11 - The Pancake Batter Anomaly

Mar/31/2008
When Sheldon gets sick the guys bail out and head for a Planet of the Apes marathon at a nearby movie theater. This leaves Penny the task of caring for the ailing eccentric genius.
Co-Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Erin Allin O'Reilly as Cheryl
Director: Mark Cendrowski
Songs: THX -- Deep Note, (Unknown artist) -- Soft Kitty

12 :01x12 - The Jerusalem Duality

Apr/14/2008
Sheldon becomes jealous of a newly hired 15 year old Korean scientific prodigy.
Guest Stars: Mark Harelik as Dr. Eric Gablehauser | Austin Lee as Dennis Kim |
Co-Guest Stars: Emma Degerstedt as Emma |
Uncredited: Joel Brooks as Professor Goldfarb
Director: Mark Cendrowski
Songs: (Unknown artist) -- Cielito Lindo

13 :01x13 - The Bat Jar Conjecture

Apr/21/2008
The guys form a team for the upcoming Physics Bowl tournament at the university but when Sheldon annoys everyone else on the team to death he gets kicked off and replaced by Leslie Winkle. Determined to win the contest, Sheldon forms his own team.
Special Guest Stars: Sara Gilbert as Leslie Winkle |
Guest Stars: Mark Harelik as Dr. Eric Gablehauser | Adam Gregor as Dimitri |
Co-Guest Stars: Sandra Marquez as Woman | Sergio Enrique as Son
Director: Mark Cendrowski
Songs: Queen -- We Are The Champions

14 :01x14 - The Nerdvana Annihilation

Apr/28/2008
They guys buy a prop from the movie The Time Machine off Ebay but when transporting the machine up to the apartment causes Penny to miss work she let's them have it in no uncertain terms.
Guest Stars: Andrew Walker as Mike
Director: Mark Cendrowski

15 :01x15 - The Pork Chop Indeterminacy

May/05/2008
When Sheldon's attractive twin sister, Missy, pays her brother a visit, Leonard, Howard, and Raj all try to make time with her to Sheldon's disapproval.
Guest Stars: Courtney Henggeler as Missy Cooper
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Lee Aronsohn, Bill Prady

16 :01x16 - The Peanut Reaction

May/12/2008
Penny decides to throw Leonard a surprise birthday party after learning he never had one as a child but things go awry quickly after she asks Sheldon for help with the party.
Guest Stars: Vernee Watson-Johnson as Althea (as Verneé Watson) | Judith Moreland as Jan |
Co-Guest Stars: Ronald Hunter as Dan | Chuck Carter as Stan
Director: Mark Cendrowski

17 :01x17 - The Tangerine Factor

May/19/2008
After Penny breaks up with her latest boyfriend Leonard finally musters up enough courage to ask her out on a date. She says yes and then goes to Sheldon for advice.
Guest Stars: James Hong as Chen |
Uncredited: William Ngo as Chinese Grad Student
Director: Mark Cendrowski

Season 2

18 :02x01 - The Bad Fish Paradigm

Sep/22/2008
Leonard and Penny's date ends abruptly then she goes to Sheldon for advice and reveals a secret about herself which he has a hard time keeping.
Co-Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

19 :02x02 - The Codpiece Topology

Sep/29/2008
After Leonard sees Penny with a new guy, he hooks up with Leslie Winkle again but the relationship hits a snag when he supports one of Sheldon't scientific theories over hers.
Guest Stars: Travis Schuldt as Eric
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Bill Prady, Lee Aronsohn

20 :02x03 - The Barbarian Sublimation

Oct/06/2008
Introduced by Sheldon to a video game, Penny soon becomes addicted to playing it to the detriment of everything else in her life.
Guest Stars: Mark Harelik as Dr. Eric Gablehauser |
Co-Guest Stars: Tyler J. Olson as Blaine | Mark Hames as Tom
Director: Mark Cendrowski

21 :02x04 - The Griffin Equivalency

Oct/13/2008
Raj gets all full of himself after making a scientific discovery and receiving a subsequent award from People magazine.
Special Guest Stars: Charlie Sheen as Himself |
Guest Stars: Mark Harelik as Dr. Eric Gablehauser | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

22 :02x05 - The Euclid Alternative

Oct/20/2008
The gang stages an intervention with Sheldon in order to force him to learn how to drive after their playing chauffeur for him begins imposing upon their time and driving them crazy.
Guest Stars: Octavia Spencer as Octavia |
Co-Guest Stars: Elena Campbell-Martinez as Maria | Livia Trevino as Lourdes
Director: Mark Cendrowski

23 :02x06 - The Cooper-Nowitzki Theorem

Nov/03/2008
A graduate student takes a liking to Sheldon and soon begins doing all his daily tasks. Our hero likes it at first but her devotion soon proves to be too much.
Guest Stars: Riki Lindhome as Ramona Nowitzki | Emily Happe as Kathy O'Brien
Director: Mark Cendrowski

24 :02x07 - The Panty Piñata Polarization

Nov/10/2008
War breaks out between Penny and Sheldon when he banishes her from the apartment for touching his food. Meanwhile, Raj and Howard try to find the location of a house full of super models.
Co-Guest Stars: Analeigh Tipton as Analeigh | Samantha Potter as Model
Director: Mark Cendrowski

25 :02x08 - The Lizard-Spock Expansion

Nov/17/2008
Howard goes on a date with a woman but when she meets Leonard she quickly ditches Howard. This leads to tension between the two nerdy friends.
Guest Stars: Sara Rue as Dr. Stephanie Barnett | Carol Ann Susi as Mrs. Wolowitz |
Co-Guest Stars: Jennifer Hale as News Announcer | Robert Clotworthy as Announcer
Director: Mark Cendrowski

26 :02x09 - The White Asparagus Triangulation

Nov/24/2008
Sheldon wholeheartedly approves of Leonard's new relationship with Stephanie and takes steps to see that it continues.
Guest Stars: Sara Rue as Dr. Stephanie Barnett
Director: Mark Cendrowski

27 :02x10 - The Vartabedian Conundrum

Dec/08/2008
When Leonard decides that he wants to end his relationship with Stephanie he goes to Penny for advice on how to do so.
Guest Stars: Sara Rue as Dr. Stephanie Barnett
Director: Mark Cendrowski

28 :02x11 - The Bath Item Gift Hypothesis

Dec/15/2008
A handsome colleague of Leonard's asks Penny out on a date. Meanwhile, Sheldon struggles to come up with an appropriate Christmas gift for Penny.
Special Guest Stars: Michael Trucco as Dr. David Underhill |
Guest Stars: Michael Hyatt as Charlotte
Director: Mark Cendrowski

29 :02x12 - The Killer Robot Instability

Jan/12/2009
The guys build a killer robot and are challenged to a duel by a colleague at the university. Meanwhile, Penny lays down the law towards Howard regarding his behavior towards her which causes him to go into a deep depression.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | John Ross Bowie as Barry Kripke
Director: Mark Cendrowski
Songs: Howard Wolowitz -- My Girl (Marcie Grossman)

30 :02x13 - The Friendship Algorithm

Jan/19/2009
When Sheldon discovers that nemesis Kripke is in charge of access to the university's super computer he decides to befriend his badly lisping colleague in hopes of gaining access.
Guest Stars: John Ross Bowie as Barry Kripke |
Co-Guest Stars: Will Deutsch as Jeremy | Jane Galloway Heitz as Mildred | Jade Zdanow as Rebecca
Director: Mark Cendrowski

31 :02x14 - The Financial Permeability

Feb/02/2009
Sheldon lends Penny money when she is unable to pay her rent. Leonard then tries to discover why she is in such a financial bind and finds out it has to do with her hulking ex-boyfriend Kurt.
Guest Stars: Brian Patrick Wade as Kurt
Director: Mark Cendrowski

32 :02x15 - The Maternal Capacitance

Feb/09/2009
Leonard's mother arrrives for a visit and proceeds to drive him, Penny, Howard, and Raj crazy. Sheldon, however, finds her fascinating and the two get along extremely well.
Special Guest Stars: Christine Baranski as Dr. Beverly Hofstadter
Director: Mark Cendrowski
Songs: Journey -- Any Way You Want It, Red Hot Chili Peppers -- Under The Bridge

33 :02x16 - The Cushion Saturation

Mar/02/2009
Penny panics when she accidentally shoots a paintball pellet onto the cushion in Sheldon's spot on the living room couch. Meanwhile, Howard begins a sexual relationship with Leslie Winkle.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski
Story: Chuck Lorre | Teleplay: Bill Prady, Lee Aronsohn

34 :02x17 - The Terminator Decoupling

Mar/09/2009
The guys travel on board a train to San Francisco for a symposium and discover that actress Summer Glau is also on board. Howard, Raj, and Leonard then develop plans to make time with her. Sheldon must rely on Penny's help after discovering that he left his flash drive behind.
Special Guest Stars: Summer Glau as Herself |
Co-Guest Stars: Dr. George Smoot as Himself | Robert Clotworthy as Conductor
Director: Mark Cendrowski

35 :02x18 - The Work Song Nanocluster

Mar/16/2009
Penny starts he own internet business but a caffeine addled Sheldon doesn't exactly help her make it into a success.
Director: Peter Chakos

36 :02x19 - The Dead Hooker Juxtaposition

Mar/30/2009
Penny get extremely jealous when a beautiful new girl moves into the apartment building and immediately has the guys at her beck and call doing favors.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Valerie Azlynn as Alicia
Director: Mark Cendrowski

37 :02x20 - The Hofstadter Isotope

Apr/13/2009
Stuart, the owner of the comic book store, gets Penny to go out on a date with him but it ends up getting ruined by Sheldon's interference. Meanwhile, Leonard, Howard, and Raj head for a single's bar to pick up women and one of them gets lucky.
Guest Stars: Kevin Sussman as Stuart |
Uncredited: Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

38 :02x21 - The Vegas Renormalization

Apr/27/2009
After Leslie Winkle breaks up with him, Raj and Leonard take Howard to Las Vegas in order to cheer him up. A prostitute they meet there named Mikayla might be just what Howard needs. Meanwhile, Sheldon, who has stayed behind, finds himself locked out of the apartment.
Guest Stars: Jodi Lyn O'Keefe as Mikayla
Director: Mark Cendrowski
Songs: Kaley Cuoco -- Soft Kitty

39 :02x22 - The Classified Materials Turbulence

May/04/2009
A second date between Penny and Stuart ends disastrously when she calls out Leonard's name during a make-out session. Meanwhile, Howard tries to fix a design flaw in a NASA space station toilet with some help from his friends.
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Robert Clotworthy as Astronaut | Travis Davis as Ground Controller |
Uncredited: Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

40 :02x23 - The Monopolar Expedition

May/11/2009
When Sheldon is chosen by the university to lead a scientific expedition to the North Pole he persuades his reluctant friends to accompany him as members of his research team. When hearing the news, Penny is sad because she realizes that she will miss Leonard while he's gone.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

Season 3

41 :03x01 - The Electric Can Opener Fluctuation

Sep/21/2009
The guys return from the North Pole but when Sheldon finds out that they tampered with the results of his experiment there he leaves for Texas in disgrace. Going to Texas to bring him back prevents Leonard from hooking up with Penny.
Special Guest Stars: Laurie Metcalf as Mary Cooper |
Guest Stars: John Ross Bowie as Barry Kripke
Director: Mark Cendrowski
Songs: Kaley Cuoco -- Soft Kitty

42 :03x02 - The Jiminy Conjecture

Sep/28/2009
Leonard and Penny's first night together is awkward. Howard and Sheldon have a major dispute over the species of a cricket found in the apartment.
Special Guest Stars: Lewis Black as Professor Crawley
Director: Mark Cendrowski
Writer: Jim Reynolds

43 :03x03 - The Gothowitz Deviation

Oct/05/2009
Sheldon discovers a way to get Penny to "behave" better while Howard and Raj dress as Goths and head to a Gothic nightclub in order to pickup women.
Guest Stars: Molly Morgan as Bethany | Sarah Buehler as Sarah | Andy MacKenzie as Skeeter
Director: Mark Cendrowski
Songs: Shania Twain -- Man! I Feel Like A Woman

44 :03x04 - The Pirate Solution

Oct/12/2009
Raj's work visa is up and his research has come to a screeching halt. The only way he can avoid returning to India is to take a job working for Sheldon.
Guest Stars: Elizabeth Bogush as Dr. Catherine Millstone | Oliver Muirhead as Professor Laughlin |
Uncredited: Elena Campbell-Martinez as Cleaning Lady
Director: Mark Cendrowski
Songs: Survivor -- Eye Of The Tiger

45 :03x05 - The Creepy Candy Coating Corollary

Oct/19/2009
Howard gets Leonard and Penny to set him up with one of her co-workers at the Cheesecake Factory and the double date goes surprisingly well. Meanwhile, Sheldon has a showdown at a card game tournament with nemesis Wil Wheaton.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Kevin Sussman as Stuart | Melissa Rauch as Bernadette Rostenkowski |
Uncredited: Owen Thayer as Lonely Larry | Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

46 :03x06 - The Cornhusker Vortex

Nov/02/2009
Seeking to learn more about football in order to impress some of Penny's friends Leonard seeks assistance from an unlikely source--Sheldon.
Guest Stars: Zachary Abel as Todd |
Co-Guest Stars: Jason Mesches as Denny
Director: Mark Cendrowski

47 :03x07 - The Guitarist Amplification

Nov/09/2009
The relationship between Leonard and Penny hits its first bump when they have an argument about an old musician friend of hers from Omaha who's arriving in town and wants to sleep on her couch. Sheldon, who hates controversy and arguments, tries to play the peacemaker.
Guest Stars: Kevin Sussman as Stuart | Carol Ann Susi as Mrs. Wolowitz | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

48 :03x08 - The Adhesive Duck Deficiency

Nov/16/2009
When Leonard, Raj, and Sheldon head out to the desert to watch a meteor shower, Sheldon is looking forward to a night alone but must come to Penny's aid when she falls in the shower and dislocates her shoulder. Meanwhile, out in the desert, hilarity ensues when they guys consume some drug laced brownies.
Director: Mark Cendrowski
Songs: Kaley Cuoco, Jim Parsons -- Soft Kitty

49 :03x09 - The Vengeance Formulation

Nov/23/2009
When Kripke pranks Sheldon during his appearance on National Public Radio our hero is determined to seek an exquisite revenge. Meanwhile, Howard begins to have second thoughts about his relationship with Bernadette.
Special Guest Stars: Katee Sackhoff as Herself |
Guest Stars: John Ross Bowie as Barry Kripke | Carol Ann Susi as Mrs. Wolowitz | Melissa Rauch as Bernadette Rostenkowski |
Co-Guest Stars: Ira Flatow as Himself
Director: Mark Cendrowski
Songs: Simon Helberg -- Bernadette

50 :03x10 - The Gorilla Experiment

Dec/07/2009
Trying to learn more about Leonard's job, Penny approaches Sheldon to teach her more about physics. Howard becomes jealous with Bernadette and Leonard start getting along.
Guest Stars: Melissa Rauch as Bernadette Rostenkowski | Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

51 :03x11 - The Maternal Congruence

Dec/14/2009
Leonard's mother pays him another visit to his and Penny's consternation and Sheldon's delight.
Special Guest Stars: Christine Baranski as Dr. Beverly Hofstadter
Director: Mark Cendrowski

52 :03x12 - The Psychic Vortex

Jan/11/2010
Leonard and Penny have an argument when he discovers that she believes in psychics while Sheldon and Raj meet two girls at a university mixer and invite them back to the apartment.
Guest Stars: Melissa Rauch as Bernadette Rostenkowski | Danica McKellar as Abby | Jen Drohan as Martha |
Co-Guest Stars: David Trice as Waiter
Director: Mark Cendrowski
Songs: The Guess Who -- American Woman

53 :03x13 - The Bozeman Reaction

Jan/18/2010
Leonard and Sheldon return home one night to discover that their apartment has been robbed and ransacked. This causes Sheldon to come unglued and make a decision to move to Bozeman, Montana.
Guest Stars: Julio Oscar Mechoso as Officer Hackett |
Co-Guest Stars: Artie O'Daly as Young Man
Director: Mark Cendrowski

54 :03x14 - The Einstein Approximation

Feb/01/2010
After getting stumped by a difficult physics problem, Sheldon cracks up and eventually goes to work with Penny at the Cheesecake Factory in order to find a solution.
Guest Stars: Melissa Rauch as Bernadette Rostenkowski | Yeardley Smith as Sandy |
Co-Guest Stars: Kevin Brief as Glen
Director: Mark Cendrowski
Songs: Murray Head -- One Night in Bangkok

55 :03x15 - The Large Hadron Collision

Feb/08/2010
After being invited to Switzerland to see the CERN Supercollider, Leonard wants Penny to join him and make it a romantic Valentine's Day getaway. Sheldon then tries to do anything to take Penny's place. But what will Leonard do when both get sick?
Director: Mark Cendrowski

56 :03x16 - The Excelsior Acquisition

Mar/01/2010
Ruining his one and only chance at meeting Stan Lee, Sheldon winds up in traffic court because of illegal driving that he did when he drove Penny to the hospital (episode 308). However, as Leonard, Howard and Raj are all going to see Stan Lee, Penny is Sheldon's only hope of avoiding jail.
Special Guest Stars: Stan Lee as Himself |
Guest Stars: Kevin Sussman as Stuart | Steve Paymer as Judge Kirby |
Co-Guest Stars: Marcus Folmar as Guard |
Uncredited: Ian Scott Rudolph as Captain Sweatpants
Director: Peter Chakos

57 :03x17 - The Precious Fragmentation

Mar/08/2010
The guys buy a box of junk at a garage sale and find something precious inside, a prop ring from The Lord of the Rings that causes friend to go against friend.
Guest Stars: Frank Maharajh as Venkatesh
Director: Mark Cendrowski

58 :03x18 - The Pants Alternative

Mar/22/2010
Sheldon wins an award and is reluctant to accept it since he must give a speech before a large crowd. Each of his friends tries to help in his/her own way.
Director: Mark Cendrowski
Songs: Jim Parsons -- The Element Song

59 :03x19 - The Wheaton Recurrence

Apr/12/2010
Leonard's relationship with Penny hits rocky water after he utters the "L" word. The guys take on a team led by Wil Wheaton in a bowling tournament.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Kevin Sussman as Stuart |
Uncredited: Ian Scott Rudolph as Captain Sweatpants | Owen Thayer as Lonely Larry
Director: Mark Cendrowski

60 :03x20 - The Spaghetti Catalyst

May/03/2010
With Leonard and Penny now split-up, Sheldon becomes the peacemaker.
Director: Anthony Rich

61 :03x21 - The Plimpton Stimulation

May/10/2010
Sheldon has a famous female physicist friend stay with he and Leonard and becomes upset when Leonard and his friend become intimate.
Guest Stars: Judy Greer as Dr. Elizabeth Plimpton
Director: Mark Cendrowski

62 :03x22 - The Staircase Implementation

May/17/2010
Leonard and Sheldon's argument leads to Leonard sleeping on Penny's couch and relating how he met Sheldon. The story of the broken elevator also is revealed.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Ally Maki as Joyce Kim |
Co-Guest Stars: Steven Yeun as Sebastian | Ajgie Kirkland as Louie | Edward Lieberman as Announcer (as Ed Lieberman)
Director: Mark Cendrowski

63 :03x23 - The Lunar Excitation

May/24/2010
Penny realizes that after dating Leonard, she can no longer put up with the guys of limited intelligence that guys she normally dates. Howard and Raj try to find Sheldon a date on the Internet.
Special Guest Stars: Sara Gilbert as Leslie Winkle |
Guest Stars: Mayim Bialik as Amy Farrah Fowler | Brian Thomas Smith as Zack |
Co-Guest Stars: Lauri Johnson as Mrs. Gunderson
Director: Peter Chakos

Season 4

64 :04x01 - The Robotic Manipulation

Sep/23/2010
Howard borrows a robotic arm from work and finds himself in a bind, literally. Penny accompanies Sheldon on his first date with new galpal Amy.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Vernee Watson-Johnson as Althea
Director: Mark Cendrowski

65 :04x02 - The Cruciferous Vegetable Amplification

Sep/30/2010
Sheldon obsesses over his limited lifespan and takes steps to ensure he will stay alive until it is possible to have his consciousness downloaded into a robot.
Special Guest Stars: Steve Wozniak as Himself
Director: Mark Cendrowski

66 :04x03 - The Zazzy Substitution

Oct/07/2010
After breaking up with Amy, Sheldon turns to feline companionship much to the dismay of all. Leonard calls on Sheldon's mother to set his roommate straight once again.
Special Guest Stars: Laurie Metcalf as Mary Cooper
Director: Mark Cendrowski

67 :04x04 - The Hot Troll Deviation

Oct/14/2010
Howard receives dating advice from Katee Sackhoff and George Takei while Sheldon and Raj engage in a nasty battle over office furniture.
Special Guest Stars: Katee Sackhoff as Herself | George Takei as Himself |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

68 :04x05 - The Desperation Emanation

Oct/21/2010
All of the guys have girlfriends except Leonard who asks Howard to set him up with one of Bernadette's friends. Sheldon decides he would be better off without Amy.
Guest Stars: Kevin Sussman as Stuart | Carol Ann Susi as Mrs. Wolowitz | Charlotte Newhouse as Joy |
Co-Guest Stars: Annie O'Donnell as Mrs. Fowler
Director: Mark Cendrowski

69 :04x06 - The Irish Pub Formulation

Oct/28/2010
When Raj's sister comes to town, Leonard rekindles a romance with her and seeks to keep that information secret from Raj with the voluntary help from Sheldon.
Guest Stars: Aarti Mann as Priya
Director: Mark Cendrowski

70 :04x07 - The Apology Insufficiency

Nov/04/2010
Howard's new project requires he get a security clearance and Sheldon's interview during the background check causes trouble. This leads to Howard terminating their friendship and Sheldon searching for a way to patch things up.
Guest Stars: Eliza Dushku as Special Agent Angela Page |
Co-Guest Stars: Neil deGrasse Tyson as Himself
Director: Mark Cendrowski

71 :04x08 - The 21-Second Excitation

Nov/11/2010
The guys decide to wait in line for a special screening of Raiders Of The Last Ark while the girls pass and have a slumber party.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Eric Andre as Joey |
Uncredited: Ian Scott Rudolph as Captain Sweatpants | Owen Thayer as Lonely Larry | Jesse Heiman as Entourage Member
Director: Mark Cendrowski

72 :04x09 - The Boyfriend Complexity

Nov/18/2010
Penny's father shows up and she asks Leonard for help by pretending to still be her boyfriend. Bernadette joins Howard and Raj spend the night using a telescope as part of an astronomy project.
Special Guest Stars: Keith Carradine as Wyatt
Director: Mark Cendrowski

73 :04x10 - The Alien Parasite Hypothesis

Dec/09/2010
A chance encounter with Zack, one of Penny's ex-boyfriends triggers an emotional response in Amy. Howard and Raj compete to decide who is a better superhero.
Guest Stars: Brian Thomas Smith as Zack
Director: Mark Cendrowski

74 :04x11 - The Justice League Recombination

Dec/16/2010
After insulting Zack, Penny's new/old boyfriend, the guys make friends and ask him to help with their entry into a New Year's Eve costume contest.
Guest Stars: Kevin Sussman as Stuart | Brian Thomas Smith as Zack |
Uncredited: Ian Scott Rudolph as Captain Sweatpants | Owen Thayer as Lonely Larry
Director: Mark Cendrowski

75 :04x12 - The Bus Pants Utilization

Jan/06/2011
Leonard has an idea for a smartphone app but as usual Sheldon tries to take over. After being kicked off the team, Penny tries to play peacemaker for him with the others.
Director: Mark Cendrowski

76 :04x13 - The Love Car Displacement

Jan/20/2011
The group goes on a road trip to attend a science event and Howard is dismayed when Bernadette encounters an ex.
Guest Stars: Rick Fox as Glenn |
Co-Guest Stars: Edward Lieberman as Announcer
Director: Anthony Rich

77 :04x14 - The Thespian Catalyst

Feb/03/2011
Sheldon turns to Penny for acting lessons as a way to improve as a teacher. Raj has inappropriate fantasies about Bernadette.
Director: Mark Cendrowski

78 :04x15 - The Benefactor Factor

Feb/10/2011
The guys attend a formal dinner to try to persuade wealthy patrons to donate to the physics department. Leonard has to decide how far he will go when a particular donor shows an interest in him.
Special Guest Stars: Jessica Walter as Mrs. Latham |
Guest Stars: Joshua Malina as President Siebert
Director: Mark Cendrowski

79 :04x16 - The Cohabitation Formulation

Feb/17/2011
Howard and Bernadette consider moving in together; Leonard resumes dating Raj's sister, over Raj's vehement objections.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Aarti Mann as Priya
Director: Mark Cendrowski

80 :04x17 - The Toast Derivation

Feb/24/2011
Sheldon decides to invite new friends over when Leonard and the rest of the gang move their gatherings to Raj's place.
Special Guest Stars: LeVar Burton as Himself |
Guest Stars: Kevin Sussman as Stuart | Brian Thomas Smith as Zack | John Ross Bowie as Barry Kripke | Aarti Mann as Priya
Director: Mark Cendrowski
Songs: John Ross Bowie, Brian Thomas Smith -- Don't Go Breakin' My Heart, Kevin Sussman, John Ross Bowie, Brian Thomas Smith -- Walking on Sunshine

81 :04x18 - The Prestidigitation Approximation

Mar/10/2011
Priya asks Leonard to choose between her and his friendship with Penny. Howard shows Sheldon a magic trick that Sheldon is determined to figure out.
Guest Stars: Aarti Mann as Priya
Director: Mark Cendrowski

82 :04x19 - The Zarnecki Incursion

Mar/31/2011
After Sheldon's World of Warcraft account is hacked, the guys take it upon themselves to confront the culprit.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Aarti Mann as Priya | Lanny Joon as Officer Shin | Christopher Douglas Reed as Todd Zarnecki
Director: Peter Chakos

83 :04x20 - The Herb Garden Germination

Apr/07/2011
Sheldon and Amy spread gossip about various members of the group as a social experiment. Howard must decide whether to pop the question to Bernadette.
Guest Stars: Aarti Mann as Priya | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali |
Co-Guest Stars: Brian Greene (2) as Himself
Director: Mark Cendrowski

84 :04x21 - The Agreement Dissection

Apr/28/2011
Priya's increased presence at Leonard and Sheldon's apartment causes changes that Sheldon struggles with. To relax, he accompanies Penny and the girls on a night out with dancing.
Guest Stars: Arnold Chun as Ho-Jun | Aarti Mann as Priya |
Co-Guest Stars: Tom Yi as Dispatcher
Director: Mark Cendrowski

85 :04x22 - The Wildebeest Implementation

May/05/2011
Amy convinces Penny and Bernadette to use Bernadette as an undercover informant on Leonard and Priya's relationship. Raj decides to try out a new drug to cure his social anxiety disorder, but the results are less than satisfactory.
Guest Stars: Aarti Mann as Priya | Tiffany DuPont as Angela |
Co-Guest Stars: Whitney Avalon as Elsie
Director: Mark Cendrowski

86 :04x23 - The Engagement Reaction

May/12/2011
Howard musters up the courage to tell his mother that he is going to marry Bernadette. The news doesn't sit well and she ends up in the hospital.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Aarti Mann as Priya | Phil Abrams as Dr. Bernstein |
Co-Guest Stars: Sharon Omi as Nurse in Biohazard Suit
Director: Howard Murray

87 :04x24 - The Roommate Transmogrification

May/19/2011
Bernadette becomes the latest person in the group to receive her Ph.D., which leads to Howard being teased about his lack of the same. When Leonard starts spending the night with Raj's sister, Raj resorts to becoming a temporary roommate of Sheldon's.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Aarti Mann as Priya | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski
Songs: Vanilla Ice -- Ice Ice Baby

Season 5

88 :05x01 - The Skank Reflex Analysis

Sep/22/2011
Penny must deal with the aftermath of her night with Raj and how it affects her friendship with the guys. Sheldon names himself captain of the paintball team and tries to assert his leadership.
Special Guest Stars: Christine Baranski as Dr. Beverly Hofstadter |
Guest Stars: Stacey Travis as Sandy
Director: Mark Cendrowski

89 :05x02 - The Infestation Hypothesis

Sep/22/2011
Sheldon insists Penny rid her apartment of a piece of "found" furniture and tries to use Amy as a go between. Leonard and Priya try to make their long distance relationship with spicy video chats.
Guest Stars: Aarti Mann as Priya | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

90 :05x03 - The Pulled Groin Extrapolation

Sep/29/2011
Leonard accompanies Amy as her date to a wedding and ends up having fun in spite of himself. Bernadette tries spending the weekend with Howard and his mother in their house.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

91 :05x04 - The Wiggly Finger Catalyst

Oct/06/2011
Raj is depressed and alone Penny fixes him up with a deaf girl to whom he can speak. Unfortunately for our hero, she turns out to be a user.
Guest Stars: Katie LeClerc as Emily | Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali
Director: Mark Cendrowski

92 :05x05 - The Russian Rocket Reaction

Oct/13/2011
Sheldon's arch nemesis Wil Wheaton invites the guys to a party at his house and Leonard decides to go, angering Sheldon. Howard gets the opportunity of a lifetime but his decision doesn't sit well with Bernadette.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Kevin Sussman as Stuart |
Uncredited: Brent Spiner as Himself | Ian Scott Rudolph as Captain Sweatpants
Director: Mark Cendrowski

93 :05x06 - The Rhinitis Revelation

Oct/20/2011
Sheldon's mom comes to town for a visit and Sheldon is angry that she doesn't want to cook and spend all her time with him. Instead, she chooses to spend most of her time with Leonard and the rest of the gang as they show her the town.
Special Guest Stars: Laurie Metcalf as Mary Cooper
Director: Howard Murray
Songs: Laurie Meltcalfe -- Soft Kitty

94 :05x07 - The Good Guy Fluctuation

Oct/27/2011
Leonard is tempted to stray on Priya when a cute girl comes on to him at the comic book store. The guys pull a Halloween prank on Sheldon and he vows revenge.
Guest Stars: Kevin Sussman as Stuart | Aarti Mann as Priya | Courtney Ford as Alice
Director: Mark Cendrowski

95 :05x08 - The Isolation Permutation

Nov/03/2011
Sheldon must suffer the responsibility to comfort Amy when Penny and Bernadette exclude her from their pre-wedding shopping.
Director: Mark Cendrowski
Songs: Mayim Bialik -- Everybody Hurts

96 :05x09 - The Ornithophobia Diffusion

Nov/10/2011
Leonard and Penny decide to spend a night out just being friends. Sheldon freaks out when a bird haunts the apartment.
Guest Stars: Blake Berris as Kevin | Ashley Austin Morris as Laura
Director: Mark Cendrowski

97 :05x10 - The Flaming Spittoon Acquisition

Nov/17/2011
Sheldon must step up his game with Amy when she decides to go out with Stuart from the comic book store.
Guest Stars: Kevin Sussman as Stuart | Josh Brener as Dale
Director: Mark Cendrowski

98 :05x11 - The Speckerman Recurrence

Dec/08/2011
To Leonard's surprise, a bully from his high school days and his own personal tormentor gets in touch with him and Leonard must decide on a course of action. The girls try to help Penny make amends for her own history of being a bully.
Guest Stars: Lance Barber as Jimmy Speckerman
Director: Anthony Rich

99 :05x12 - The Shiny Trinket Maneuver

Jan/12/2012
Amy is upset with Sheldon and his dismissal of her career accomplishments. Howard is dismayed by Bernadette's apparent disinterest in kids.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Jonathan Schmock as Jonathan |
Co-Guest Stars: Jadon Sand as Aaron | Dusan Brown as Jeremy
Director: Mark Cendrowski

100 :05x13 - The Recombination Hypothesis

Jan/19/2012
Out of the blue, Leonard invites Penny out on a date and they struggle with what it means.
Co-Guest Stars: Jim Turner (2) as Reverend White
Director: Mark Cendrowski

101 :05x14 - The Beta Test Initiation

Jan/26/2012
Leonard proposes that he and Penny treat their dating like software development and report "bugs" to each other. Raj gets a new phone, and falls in love with the AI contained within.
Guest Stars: John Ross Bowie as Barry Kripke | Becky O'Donohue as Siri |
Co-Guest Stars: Kevin Brief as Security Guard
Director: Mark Cendrowski

102 :05x15 - The Friendship Contraction

Feb/02/2012
Leonard finally tires of Sheldon's thankless demands on him and breaks the friendship agreement. Howard and Raj brainstorm a way to make the other NASA astronauts pick a cool nickname for Howard.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Kevin Sussman as Stuart |
Co-Guest Stars: Michael J. Massimino as Himself (as Mike Massimino)
Director: Mark Cendrowski
Songs: Elton John -- Rocket Man

103 :05x16 - The Vacation Solution

Feb/09/2012
Sheldon's is required to take some vacation time away from work, and Amy pays the price. A pre-nuptial agreement rears its ugly head between Howard and Bernadette.
Guest Stars: Joshua Malina as President Siebert |
Co-Guest Stars: Nick Clifford as Phil
Director: Mark Cendrowski
Songs: Black Eyed Peas -- I Gotta Feeling

104 :05x17 - The Rothman Disintegration

Feb/16/2012
Sheldon and his nemesis Kripke both want an office that becomes available with the retirement of a senior physicist. Amy gives Penny a heartfelt gift that Penny abhors, but how does she tell Amy without hurting her?
Guest Stars: Joshua Malina as President Siebert |
Co-Guest Stars: John Ross Bowie as Barry Kripke | Lynn Seibel as Professor Rothman (as Lynn Phillip Seibel)
Director: Mark Cendrowski

105 :05x18 - The Werewolf Transformation

Feb/23/2012
When Sheldon's barber becomes unavailable due to illness, it starts the descent of his orderly life into chaos. Astronaut training proves more difficult for Howard than expected.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Vernee Watson-Johnson as Althea | Peter Onorati as Angelo
Director: Mark Cendrowski
Songs: Bon Jovi -- Wanted Dead or Alive

106 :05x19 - The Weekend Vortex

Mar/08/2012
The guys decide to spend the weekend playing video games like they used to. The women in their life have other ideas however, especially Amy who is counting on Sheldon accompanying her to a family event.
Guest Stars: Kevin Sussman as Stuart | Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

107 :05x20 - The Transporter Malfunction

Mar/29/2012
Raj finally gives up and asks his parents for help to find a wife. Sheldon's conscience causes him to hear his toy Spock doll speak to him.
Guest Stars: Brian George (1) as Dr. Koothrappali | Alice Amter as Mrs. Koothrappali | Chriselle Almeida as Lakshmi |
Uncredited: Leonard Nimoy as Spock
Director: Mark Cendrowski

108 :05x21 - The Hawking Excitation

Apr/05/2012
Howard takes advantage of Sheldon's obsession to meet visiting professor Stephen Hawking by putting him through the ringer.
Special Guest Stars: Stephen Hawking as Himself |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

109 :05x22 - The Stag Convergence

Apr/26/2012
Howard's bachelor party results in Bernadette learning things about Howard's past that makes her reconsider marrying him.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Kevin Sussman as Stuart | John Ross Bowie as Barry Kripke |
Uncredited: Ian Scott Rudolph as Captain Sweatpants | Jesse Heiman as Bachelor Party Guest
Director: Peter Chakos

110 :05x23 - The Launch Acceleration

May/03/2012
Howard's mission into space gets rescheduled sooner, creating a conflict with the wedding. Leonard and Penny resume their physical relationship until Leonard says something he shouldn't in the boudoir. Amy uses psychology on Sheldon to bring them closer together.
Guest Stars: Casey Sander as Mike Rostenkowski |
Co-Guest Stars: Karl T. Wright as Jimmy | Robert Clotworthy as Dave Roeger
Director: Mark Cendrowski

111 :05x24 - The Countdown Reflection

May/10/2012
Bernadette decides she wants to be married to Howard before his mission to space. The gang scrambles to get it done.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Casey Sander as Mike Rostenkowski | Pavel Lychnikoff as Dimitri (as Pasha Lychnikoff) |
Co-Guest Stars: Michael J. Massimino as Himself (as Mike Massimino) | Amy Tolsky as Joan | Endre Hules as Russian Mission Control
Director: Mark Cendrowski

Season 6

112 :06x01 - The Date Night Variable

Sep/27/2012
With everyone paired up, Raj is left alone and imposes himself on others. Howard cannot escape the two women in his life, even while on the space station.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Pavel Lychnikoff as Dimitri
Director: Mark Cendrowski

113 :06x02 - The Decoupling Fluctuation

Oct/04/2012
Penny confides to Amy and Bernadette that she is unsure about staying with Leonard, and when Sheldon inevitably learns about it, he takes matters into his own hands. Howard gets pranked as the new guy in space.
Guest Stars: Pavel Lychnikoff as Dimitri | Kevin Sussman as Stuart |
Co-Guest Stars: Michael J. Massimino as Himself
Director: Mark Cendrowski

114 :06x03 - The Higgs Boson Observation

Oct/11/2012
Sheldon hires a young woman to be his assistant, which initially makes Amy jealous, then later Penny finds cause for concern. On the space station, Howard starts to freak out when he learns his return to Earth will be delayed.
Guest Stars: Pavel Lychnikoff as Dimitri | Margo Harshman as Alex Jensen
Director: Mark Cendrowski

115 :06x04 - The Re-Entry Minimization

Oct/18/2012
Howard is home, but on his first night back Bernadette gets sick so he decides to visit his friends. His reception is not what he expected. Game Night with Sheldon, Leonard, Penny and Amy takes a competitive turn when the girls take on the guys.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Pavel Lychnikoff as Dimitri | Ken Lerner as Dr. Schneider | Jan Hoag as Lilian | John Mendoza as Chauffeur | Kevin Sussman as Stuart |
Co-Guest Stars: Michael J. Massimino as Himself |
Uncredited: Howie Mandel as Himself
Director: Mark Cendrowski
Songs: Elton John -- Rocket Man

116 :06x05 - The Holographic Excitation

Oct/25/2012
Raj and Stuart throw a Halloween bash at the comic book store. Howard is upset when everyone tires of his stories about life on the space station. Leonard shows Penny his laboratory and is surprised by her reaction.
Special Guest Stars: Buzz Aldrin as Himself |
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Janelle Giumarra as Claire (as Janelle Marra)
Director: Mark Cendrowski

117 :06x06 - The Extract Obliteration

Nov/01/2012
Penny reveals that she is taking a class at the local community college, but insists it is no big deal. Sheldon plays an Internet game with his idol, Stephen Hawking, then frets when Hawking stops playing.
Guest Stars: Stephen Hawking as Himself
Director: Mark Cendrowski

118 :06x07 - The Habitation Configuration

Nov/08/2012
Bernadette puts her foot down about Howard moving out of his mom's house. Sheldon is perplexed with the enmity between Amy and his friend Wil Wheaton and has no clue how to fix it.
Special Guest Stars: Wil Wheaton as Himself | LeVar Burton as Himself |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

119 :06x08 - The 43 Peculiarity

Nov/15/2012
Howard is curious why Sheldon disappears every day at 2:45 and asks Raj to help him discover the secret. Penny's new school partner causes Leonard to be jealous.
Guest Stars: Margo Harshman as Alex Jensen | Ryan Cartwright as Cole
Director: Mark Cendrowski

120 :06x09 - The Parking Spot Escalation

Nov/29/2012
The University decides to reassign Sheldon's unused parking space to the newly popular Howard, a move that Sheldon feels is a slap in the face to his importance. This starts a feud between the two friends that spills over to their ladies, and Penny pays the price.
Guest Stars: William Stanford Davis as Dry Cleaner
Director: Peter Chakos

121 :06x10 - The Fish Guts Displacement

Dec/06/2012
When Amy gets sick, Sheldon is required to take care of her and she milks it for all it's worth. Bernadette arranges for Howard and her father to bond via a fishing trip.
Guest Stars: Casey Sander as Mike Rostenkowski | Meagen Fay as Mrs. Rostenkowski
Director: Mark Cendrowski
Songs: Katrina & The Waves -- Walking on Sunshine

122 :06x11 - The Santa Simulation

Dec/13/2012
Leonard leads the boys on a Christmasy version of Dungeons and Dragons, while Raj joins the girls on their night out and they try to find him a girl.
Guest Stars: Dakin Matthews as Santa Claus | Kevin Sussman as Stuart
Director: Mark Cendrowski

123 :06x12 - The Egg Salad Equivalency

Jan/03/2013
Sheldon manages to put his foot in his mouth and ends up being accused of sexual harassment. In typical fashion, he throws his friends under the bus too.
Special Guest Stars: Regina King as Mrs. Davis |
Guest Stars: Margo Harshman as Alex Jensen
Director: Mark Cendrowski

124 :06x13 - The Bakersfield Expedition

Jan/10/2013
The guys head out to a comic book convention and get stranded in full costume when Leonard's car is stolen. The girls decide to try to understand their men and end up in a heated debate over a comic book character.
Guest Stars: Matt Battaglia as Officer Reynolds | Angela Sargeant as Lana | Kevin Sussman as Stuart |
Co-Guest Stars: Craig Gellis as Car Thief #1 | Frank Alvarez as Car Thief #2 | Rick Gifford as Guy |
Uncredited: Ian Scott Rudolph as Captain Sweatpants | Owen Thayer as Lonely Larry
Director: Mark Cendrowski

125 :06x14 - The Cooper/Kripke Inversion

Jan/31/2013
After being forced to team up with Barry Kripke by management, Sheldon is dismayed when he discovers his work is not up to par with Kripke's. Howard and Raj spare no expense to get action figures that look like themselves.
Guest Stars: John Ross Bowie as Barry Kripke
Director: Mark Cendrowski

126 :06x15 - The Spoiler Alert Segmentation

Feb/07/2013
Leonard finally has enough of Sheldon and moves out, to Penny's distress. Amy takes advantage of Sheldon's need for a new roommate, to Sheldon's distress. While Howard is away, Raj agrees to look in on Mrs. Wolowitz, to his distress!
Guest Stars: Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

127 :06x16 - The Tangible Affection Proof

Feb/14/2013
The three couples celebrate Valentine's day in their own way, with little success while Raj and Stuart throw a party for their unattached friends.
Guest Stars: Kevin Sussman as Stuart | Margo Harshman as Alex Jensen | Josh Brener as Dale | Kate Micucci as Lucy |
Co-Guest Stars: Briana Cuoco as Gretchen |
Uncredited: Jesse Heiman as Comic Book Store Nerd
Director: Mark Cendrowski

128 :06x17 - The Monster Isolation

Feb/21/2013
When Raj gets dumped again, he decides to never leave his apartment or have anything to do with girls. Penny uses her acting skills to help Sheldon with his "Fun With Flags" videos.
Guest Stars: Kevin Sussman as Stuart | Kate Micucci as Lucy |
Co-Guest Stars: Riccardo Lebron as Tom
Director: Mark Cendrowski

129 :06x18 - The Contractual Obligation Implementation

Mar/07/2013
While Leonard, Sheldon, and Howard try to motivate middle school girls to pursue a career in science, the ladies play hooky and go to Disneyland. Raj has a first date with Lucy.
Guest Stars: Kate Micucci as Lucy | Brian Posehn as Bert | Piper MacKenzie Harris as Girl #1 |
Co-Guest Stars: Diamond White as Girl #2 | Dawson Fletcher as Justin
Director: Mark Cendrowski

130 :06x19 - The Closet Reconfiguration

Mar/14/2013
Howard and Bernadette trick Sheldon into organizing their closet where he finds an unopened letter from Howard's father. Howard then struggles whether or not to read it.
Director: Anthony Rich

131 :06x20 - The Tenure Turbulence

Apr/04/2013
A tenured position becomes available at the University and Leonard, Sheldon, Raj, and the lisping Barry Kripke all decide to apply, each with their own unique style of currying favor.
Special Guest Stars: Regina King as Mrs. Davis |
Guest Stars: John Ross Bowie as Barry Kripke
Director: Mark Cendrowski

132 :06x21 - The Closure Alternative

Apr/25/2013
Raj's curiosity about his new love interest leads him to discover something to make him change the impression he makes on people. Meanwhile Penny worries that she lacks passion about anything and Amy tries to cure Sheldon of his completion compulsion.
Guest Stars: Kate Micucci as Lucy
Director: Mark Cendrowski

133 :06x22 - The Proton Resurgence

May/02/2013
Sheldon learns that his childhood television idol, Professor Proton, is still alive and hiring himself out for parties, so of course Sheldon hires him to perform. Raj is away for the weekend so he asks Howard and Bernadette to look after his dog, with the expected result.
Special Guest Stars: Bob Newhart as Arthur Jeffries (Professor Proton) |
Guest Stars: Troy Winbush as Paramedic
Director: Mark Cendrowski
Songs: Jim Parsons -- Soft Kitty

134 :06x23 - The Love Spell Potential

May/09/2013
The girls join the boys in a game of Dungeons & Dragons after their trip to Las Vegas falls through. Raj and Lucy continue their dating adventures and Raj pushes Lucy to confront one of her greatest fears.
Guest Stars: Kate Micucci as Lucy | David Trice as Waiter
Director: Anthony Rich

135 :06x24 - The Bon Voyage Reaction

May/16/2013
Leonard gets an opportunity to work with Dr. Stephen Hawking, but the downside is it will mean being away for up to four months. Both Penny and Sheldon are affected tremendously and both try to come to terms with their feelings while still supporting Leonard. Raj risks everything with Lucy when he pushes her too hard and too fast.
Guest Stars: Kate Micucci as Lucy
Director: Mark Cendrowski

Season 7

136 :07x01 - The Hofstadter Insufficiency

Sep/26/2013
Sheldon and Penny commiserate over their mutual sadness of Leonard's absence. Howard encourages Raj to start looking for another girlfriend and is surprised at who he chooses. Amy & Bernadette are away at a conference and bond/clash when they talk about their relationships.
Special Guest Stars: Regina King as Mrs. Davis |
Co-Guest Stars: Sophie Tamiko Oda as Grace (as Sophie Oda) | Aaron Takahashi as Scientist | Alex Ball as Waiter
Director: Mark Cendrowski

137 :07x02 - The Deception Verification

Sep/26/2013
Leonard arrives home early and chooses not to tell Sheldon. Howard's unusual behavior results from an unlikely source.
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Barak Hardley as Pizza Delivery Guy
Director: Mark Cendrowski

138 :07x03 - The Scavenger Vortex

Oct/03/2013
After the entire gang passes on Raj's dinner party, he designs a scavenger hunt that brings out unknown personality traits in his friends.
Guest Stars: Kevin Sussman as Stuart
Director: Mark Cendrowski
Songs: Neil Diamond -- America, Neil Diamond -- Cherry, Cherry, Neil Diamond -- Love On The Rocks, Neil Diamond -- Sweet Caroline

139 :07x04 - The Raiders Minimization

Oct/10/2013
Sheldon looks to exact revenge from Amy after she ruins Raiders of The Lost Ark by revealing a plot hole. Leonard uses guilt as leverage over Penny, and Raj and Stuart try the Internet to find a date.
Special Guest Stars: Christine Baranski as Dr. Beverly Hofstader |
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Christine Corpuz as Woman
Director: Mark Cendrowski
Songs: London Symphony Orchestra -- The Raiders March, John Williams (3) -- The Raiders March

140 :07x05 - The Workplace Proximity

Oct/17/2013
When Amy starts working at the same university as Sheldon, friction between the pair spreads to Howard and Bernadette.
Co-Guest Stars: Todd Eric Andrews as Dr. Gunderson | Ayumi Iizuka as Scientist
Director: Mark Cendrowski

141 :07x06 - The Romance Resonance

Oct/24/2013
Sheldon is insufferable after making a major scientific discovery, or did he? Howard plans an elaborate romantic celebration for Bernadette and Penny decides she needs to do something for Leonard.
Co-Guest Stars: Tom Fonss as Student
Director: Mark Cendrowski
Songs: The Big Bang Theory Choir -- Bernadette

142 :07x07 - The Proton Displacement

Nov/07/2013
A chance encounter with Professor Proton ends up hurting Sheldon's feelings when his childhood hero looks to Leonard for professional advice. Raj's special bonding time with the girls is hijacked by Howard.
Special Guest Stars: Bob Newhart as Arthur Jeffries (Professor Proton) |
Guest Stars: Bill Nye as Himself
Director: Mark Cendrowski

143 :07x08 - The Itchy Brain Simulation

Nov/14/2013
Leonard uncovers a situation that he is sure will make Sheldon "freak-out", but Sheldon comes up with a compromise that ends up punishing Leonard. Penny encounters Raj's ex-girlfriend and can't help herself from intruding into his love life.
Guest Stars: Kate Micucci as Lucy | Morgan Hewitt as Lizzy
Director: Mark Cendrowski

144 :07x09 - The Thanksgiving Decoupling

Nov/21/2013
Howard invites everyone to his mother's house for Thanksgiving where unexpected drama emerges from Penny's past and Howard's father-in-law bonds with an unlikely person.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Casey Sander as Mike Rostenkowski | Brian Thomas Smith as Zack
Director: Mark Cendrowski

145 :07x10 - The Discovery Dissipation

Dec/05/2013
Sheldon's disgust at his accidental discovery and subsequent fame reach a level that compels Leonard and Amy to try to mollify him. Raj needs a temporary place to stay for a week so Howard invites him to stay with he and Bernadette.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: John Ross Bowie as Barry Kripke |
Co-Guest Stars: Ira Flatow as Himself
Director: Mark Cendrowski

146 :07x11 - The Cooper Extraction

Dec/12/2013
Sheldon goes home to Texas to be with his family during the birth of his sister's baby and the gang reminisces about what their life would be life if they never met him.
Special Guest Stars: Laurie Metcalf as Mary Cooper |
Guest Stars: Kevin Sussman as Stuart | Carol Ann Susi as Mrs. Wolowitz | Brian Thomas Smith as Zack
Director: Mark Cendrowski

147 :07x12 - The Hesitation Ramification

Jan/02/2014
Penny finally gets her big break, or does she? Her reaction leads her to make Leonard an offer that is difficult for him to accept. Sheldon tries to quantize humor while Raj and Stuart go to the mall to practice talking to girls.
Guest Stars: Kevin Sussman as Stuart |
Co-Guest Stars: Marcus Folmar as Security Guard
Director: Mark Cendrowski

148 :07x13 - The Occupation Recalibration

Jan/09/2014
Penny takes a drastic step to further her career. While Leonard says he supports her decision, he has his doubts. Sheldon is forced to take some vacation time and ends up hanging with Penny. While Amy fends off an unwanted suitor, Bernadette tries to find a replacement comic book she accidentally damaged.
Guest Stars: Josh Peck as Jesse | Kevin Sussman as Stuart | Brian Posehn as Bert |
Co-Guest Stars: Ian Scott Rudolph as Captain Sweatpants | Edward Lieberman as Man
Director: Mark Cendrowski

149 :07x14 - The Convention Conundrum

Jan/30/2014
The guys fail to get tickets to Comic-Con and debate whether to buy them from a scalper. Sheldon refuses to and decides to start his own comic book convention and he targets James Earl Jones as a potential panelist. While the guys are occupied with "childish" endeavors, the ladies decide to do something "grown-up".
Special Guest Stars: James Earl Jones as Himself | Carrie Fisher as Herself
Director: Mark Cendrowski

150 :07x15 - The Locomotive Manipulation

Feb/06/2014
Amy treats Sheldon to a train trip as incentive for a romantic Valentine's Day getaway. Raj leaves his dog in the not so capable hands of Penny and Leonard.
Guest Stars: Tania Raymonde as Yvette | Eric Petersen as Eric | Alex Ball as Waiter
Director: Mark Cendrowski

151 :07x16 - The Table Polarization

Feb/27/2014
At Penny's urging, Leonard stands up to Sheldon and buys a dining room table while Howard and Bernadette contemplate a return to the space station for Howard.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Casey Sander as Mike Rostenkowski | Christopher Neiman as Dr. Dreyfus |
Co-Guest Stars: Michael J. Massimino as Himself
Director: Gay Linvill

152 :07x17 - The Friendship Turbulence

Mar/06/2014
Howard takes Bernadette's comments seriously about he and Sheldon's bickering and invites Sheldon to fly with him to NASA at Houston. Penny's career luck continues its downward slide while Raj asks Amy to be his wingman on an online dating service.
Guest Stars: Laura Spencer as Emily Sweeney |
Co-Guest Stars: Gilda Stratton as Flight Attendant
Director: Mark Cendrowski

153 :07x18 - The Mommy Observation

Mar/13/2014
Sheldon decides to surprise his mother with a visit since he is already in Texas with Howard, but he is the one who gets the big surprise. Raj puts on another of his dinner parties that leads to some conflict within the group.
Special Guest Stars: Laurie Metcalf as Mary Cooper |
Guest Stars: Kevin Sussman as Stuart
Director: Mark Cendrowski

154 :07x19 - The Indecision Amalgamation

Apr/03/2014
An episode about choices: Raj is faced with the possibility of dating two women; Penny must decide whether to take a role in a bad movie; Sheldon must choose between buying an X-Box One or PS4.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Laura Spencer as Emily Sweeney |
Co-Guest Stars: Fernando Rivera as Salesperson | Rod Keller as Wardrobe Person
Director: Anthony Rich

155 :07x20 - The Relationship Diremption

Apr/10/2014
Sheldon comes to the depressing realization that is life long research into string theory has been for naught. Howard and Bernadette join Raj and his new girlfriend Emily on a double date, which turns out to be a night Howard would just as soon forget.
Guest Stars: John Ross Bowie as Barry Kripke | Laura Spencer as Emily Sweeney | Stephen Hawking as Himself |
Co-Guest Stars: Phyllis Timbes as Voicemail
Director: Mark Cendrowski

156 :07x21 - The Anything Can Happen Recurrence

Apr/24/2014
Penny encourages a return to "Anything Can Happen Thursdays" as a way of getting Sheldon's mind off his career funk. Amy and Bernadette get caught in a lie while Howard helps Raj prepare for his date night with Emily.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Laura Spencer as Emily Sweeney | Kimberly Hebert-Gregory as Ms. Davora
Director: Mark Cendrowski

157 :07x22 - The Proton Transmogrification

May/01/2014
The loss of Sheldon's idol Professor Proton provokes feelings that Sheldon cannot seem to process. Leonard enjoys torturing Penny about their numerous marriage proposals while Amy and Bernadette decide to make a surprise to help celebrate "Star Wars Day."
Special Guest Stars: Bob Newhart as Arthur Jeffries (Professor Proton)
Director: Mark Cendrowski

158 :07x23 - The Gorilla Dissolution

May/08/2014
Penny's role in the gorilla movie leads her to rethink the choices she has made, both in her career and her life. Howard and Bernadette care for an injured Mrs. Wolowitz, a dry run for a potential child down the road while Raj seeks advice from Sheldon when he sees Emily on a date with another man.
Special Guest Stars: Wil Wheaton as Himself |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Laura Spencer as Emily Sweeney | Steve Valentine as Kenneth |
Co-Guest Stars: Beau Casper Smart as Travis | Kaliko Kauahi as Marta
Director: Peter Chakos

159 :07x24 - The Status Quo Combustion

May/15/2014
The realization of Leonard and Penny's engagement and future without him suddenly sinks in to Sheldon, and the stress it adds to his already failing career induces panic. Meanwhile, Howard and Bernadette desperately search for assistance caring for Howard's mother.
Special Guest Stars: Christine Baranski as Dr. Beverly Hofstader |
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Kevin Sussman as Stuart |
Co-Guest Stars: Monica Garcia as Maria
Director: Mark Cendrowski

Season 8

160 :08x01 - The Locomotion Interruption

Sep/22/2014
Leonard and Amy end up taking an unexpected road trip to Arizona to go get Sheldon. Penny has an interview for a job at Bernadette's company. Stuart's relationship with Mrs. Wolowitz freaks out Howard.
Guest Stars: Carol Ann Susi as Mrs. Wolowitz | Kevin Sussman as Stuart | Stephen Root as Don | David Barrera as Officer Hernandez | Robert Noble as Older Gentleman | Tonja Kahlens as Woman | Anil Margsahayam as Man
Director: Mark Cendrowski

161 :08x02 - The Junior Professor Solution

Sep/22/2014
After Sheldon is forced to teach a class, Howard manages to surprise everybody by taking it. Amy plays both Penny and Bernadette as the tension between them increases in regards to Penny's training for her new job at Bernadette's company.
Guest Stars: Regina King as Mrs. Davis
Director: Mark Cendrowski

162 :08x03 - The First Pitch Insufficiency

Sep/29/2014
Wolowitz feels really nervous when NASA asks him to throw out the first pitch at a Los Angeles Angels game. Leonard and Penny attempt to show Sheldon he is wrong after he says that he and Amy are a "superior couple."
Guest Stars: Michael J. Massimino as Himself | Malcolm Foster Smith as Roy | Michael Araujo as Stadium Announcer
Director: Mark Cendrowski

163 :08x04 - The Hook-Up Reverberation

Oct/06/2014
Penny receives the cold shoulder from Raj's girlfriend after he tells her some information about their past history. The boys think about buying into Stuart's comic-book emporium.
Guest Stars: Kevin Sussman as Stuart | Laura Spencer as Emily Sweeney
Director: Mark Cendrowski

164 :08x05 - The Focus Attenuation

Oct/13/2014
After the guys decide to have a physicist's retreat, the girls head to Las Vegas for the weekend.
Director: Mark Cendrowski

165 :08x06 - The Expedition Approximation

Oct/20/2014
Penny receives a company car from the pharmaceutical company where she's now employed but has trouble coming up with the money to pay back Leonard for the one he bought for her. Meanwhile, Sheldon and Raj look at a potential research grant.
Director: Mark Cendrowski
Songs: Merle Travis -- Dark as a Dungeon

166 :08x07 - The Misinterpretation Agitation

Oct/30/2014
At her new job, Penny has a client who develops a crush on her. It turns out that he is a middle-aged version of Howard Wolowitz. Amy and Bernadette argue over a photo shoot of female scientists.
Special Guest Stars: Billy Bob Thornton as Dr. Oliver Lorvis |
Guest Stars: Annie O'Donnell as Mrs. Lorvis
Director: Mark Cendrowski

167 :08x08 - The Prom Equivalency

Nov/06/2014
Amy, Bernadette, and Penny decide to re-enact their high school proms with their respective fellows. Raj, Emily, and Stuart are included too.
Guest Stars: Laura Spencer as Emily Sweeney | Kevin Sussman as Stuart | Kara Luiz as Jeanie | Carol Ann Susi as Mrs. Wolowitz
Director: Mark Cendrowski

168 :08x09 - The Septum Deviation

Nov/13/2014
Sheldon panics when Leonard goes into the hospital for an operation. Meanwhile, Raj learns that his parents have gotten a divorce.
Director: Anthony Rich

169 :08x10 - The Champagne Reflection

Nov/20/2014
Sheldon retires his Fun With Flags You Tube series, while Leonard, Howard, and Raj look through the papers of a deceased colleague and Bernadette discovers what her boss really thinks of her.
Special Guest Stars: LeVar Burton as Himself |
Guest Stars: John Ross Bowie as Barry Kripke | Stephen Root as Don | Paul Wilson (1) as Professor Sharpe
Director: Mark Cendrowski

170 :08x11 - The Clean Room Infiltration

Dec/11/2014
Amy fixes a traditional Victorian Era Christmas Eve dinner whose guest list includes Raj's newly separated father, visiting from India.
Guest Stars: Brian George (1) as Dr. Koothrappali | Dakin Matthews as Santa Claus
Director: Mark Cendrowski
Songs: Covered by Bernadette -- Here Comes Santa Claus, Covered by Leonard, Howard, and Raj -- Jingle Bells

171 :08x12 - The Space Probe Disintegration

Jan/08/2015
Raj is concerned over whether a probe he designed will work in outer space. Penny and Amy coerce Leonard and Sheldon into taking them shopping.
Director: Mark Cendrowski

172 :08x13 - The Anxiety Optimization

Jan/15/2015
The gang tries to help Sheldon when he becomes stuck in a rut at work by increasing his anxiety level. Howard teases Raj with a new game called "Cinnamon or Emily?"
Guest Stars: Laura Spencer as Emily Sweeney
Director: Mark Cendrowski
Songs: Johnny Galecki, Kaley Cuoco -- Soft Kitty
Warning: The Big Bang Theory guide may contain spoilers
Classification: Scripted
Genre: Comedy
Status: Returning Series
Network: CBS ( USA)
Airs: Thursdays at 08:00 pm
Runtime: 30 Minutes
Premiere: September 24, 2007
Episode Order: 24
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