1 :01x01 - And Then There Were Ten

When the bell rings at school, school is finally over and it's time for Ben Tennyson to go camping with Grandpa Max, but his cousin, Gwen, is coming too. At the campsite, Ben goes out in the forest and discovers a device named the Omnitrix and it jumps on to him. Now he can transform into ten different aliens.

2 :01x02 - Washington B.C.

Ben must battle the Dr. Amino, a mad scientist and must him from running rampant in Washington, D.C. with an invention that can mutate dinosaurs and mutate ordinary animals into scary monsters.

3 :01x03 - The Krakken

While at a lakefront campsite, Ben has a encounter that was with chance with a sea monster called a Krakken. Initially, Max and Gwen don't believe Ben saw that, but when the Krakken steps up its attacks, Ben must use his form that is aquatic - Ripjaw - to make things right.

4 :01x04 - Permanent Retirement

Grandpa, Gwen and Ben visit Aunt Vera at a retirement center for the weekend after capturing villains that were trying to steal an ATM, but there is something weird happening at the retirement center. Aliens called the Limax are taking over the retirement center, so Ben has to stop them.

5 :01x05 - Hunted

Vilgax sends three expert alien bounty hunters to get the Omnitrix. They are the crustacean like Kraab, the assisin who is mechanical called Sixsix and Hoverboard, the mysterious one. Ben learns that there is more than one way to beat an enemy and that things aren't always what they seem.

6 :01x06 - Tourist Trap

When Ben changes into an alien to play a prank on a lame town called Sparksville filled with cheesy tourist exhibits, the unusual energy from the prototype helps to release little creatures called Megawatts, mischievious and destructive creatures made of electrical energy.

7 :01x07 - Kevin 11

After being kicked out of a hotel, Grandpa Max starts to argue with Ben and he goes out to the city, where he finds a sociopath named Kevin. He can absorb most types of energy, but he may just trying to steal the Omnitrix.

8 :01x08 - The Alliance

As Fourarms, Ben outwits an armored truck robbery by a Joey, a gangleader who is female. But when they meet again, Ben finds that Joey has merged with parts of Vilgax's robot drones to become Rojo, an alien cyborg. What's more? When Upgrade goes into her mind, he gets a disturbing message.

9 :01x09 - Last Laugh

Ben's fear of clowns comes up at a bad time when he comes across a villainous circus with a psychic clown. He is also a vampire named Zombozo. Also, Gwen is in danger and now Ben has to overcome his fear.

10 :01x10 - Lucky Girl

XLR8 is used by Ben to defeat a magician called Hexlord who uses charms to get his powers. When Gwen gets one of the magical charms, she finds that it gives her a lot of luck in battles and becomes a hero named Lucky Girl.

11 :01x11 - A Small Problem

Because he isn't tall enough, Ben doesn't get to go to a ride at a water park. He tries to change into an alien, but instead, he ends up as Greymatter. Now, a geek who likes sci-fi captures him and gives him to an organization.

12 :01x12 - Side Effects

Councilwoman Lang's tries to develop a downtown area in the city again, which disturbs a man named Clancy. As Upgrade, Ben tries to stop a villain. He finds an ice cream truck and gets in it, but gets trapped in there when getting an ice cream. Now he has a cold and what's worse is that the Omnitrix and his forms are weakened by the cold. When Clancy makes threats to the city by causing a meltdown at a power plant and captures Councilwoman Liang, Ben attempts to stop him while dealing with his cold's side effects.

13 :01x13 - Secrets

Healed from his injuries, Vilgax decides to come after the prototype himself, landing on Earth and causing mayhem to flush out the holder of the device. Meanwhile, in this episode, Grandpa Max's very mysterious past is brought up which includes a story with Vilgax that is very personal that combines in the final showdown between the Tennyson family that's combined and Vilgax.

14 :02x01 - Truth

Grandpa Max tells the story of how he used to be part of "The Plumbers", a group of people who capture extraterrestrial creatures to Ben after the battle with Vilgax. Also in this episode, they meet an old partner of Grandpa Max named Phil, however they learn that Phil steals a device called the Null Void Projector. He releases the aliens captured in there and releases them to make money.

15 :02x02 - The Big Tick

Ben turns into a new alien form while being at Yellowstone Park. A meteor suddenly crashes into the park and a creature called "The Tremendous One" emerges. Aliens who worship The Tremendous One also come out. They try to use it to make the Earth vanish. Can Ben stop them?

16 :02x03 - Framed

Grandpa Max, Ben, and Gwen are outside a video game store waiting to buy the new Sumo Slammer video game. Gwen and Grandpa Max go to a book store and when they leave, they notice that Four Arms is attacking people. When they go to the RV, they discover that Ben is there and Gwen yells at him. Ben goes out and finds the alien who keeps attacking people and it turns out that it is actually Kevin seeking revenge on Ben. He must stop him and at the same time doesn't expose his identity to the government.

17 :02x04 - Gwen 10

Ben tries to transform into Four Arms to stop two robbers from robbing a gas station, however he discovers that the Omnitrix is gone. When he asks Grandpa Max where it is, it turns out that he doesn't know what it is. Why? It is because this is the day Ben is supposed to get the watch. Events from the day start to repeat including the crash involving the meteor. He tries to find the watch at the crash and notices that Gwen already got it.

18 :02x05 - Grudge Match

Ben and Kevin 11 try to escape a space ship by teaming up.

19 :02x06 - The Galactic Enforcers

A group of super heroes are searching for a bounty hunter and Ben joins them.

20 :02x07 - Camp Fear

Ben discovers another alien hero when he works with Gwen and Max to try to contain otherworldly mushrooms that have taken over a summer camp.

21 :02x08 - The Ultimate Weapon

Grandpa Max becomes so consumed with finding an alien weapon that's been unearthed in Texas that he's willing to do battle with the Forever Knights.

22 :02x09 - Tough Luck

Gwen's magic powers return when she buys a stone in Las Vegas, but Hex and his niece want the same item and pursue Gwen to get it.

23 :02x10 - They Lurk Below

Aliens threaten to destroy an underwater resort built by Max's old friend.

24 :02x11 - Ghost Freaked Out

One of Ben's alien personalities escapes from his watch and ends up wreaking havoc.

25 :02x12 - Dr. Animo and the Mutant Ray

Ben plays around with his Omnitrix and an important piece falls out, causing him to transform into many bizarre alien combinations. Meanwhile, Dr. Animo takes it away from Ben and uses it for his ray, which can be used to turn animals and humans into Ben's aliens.

26 :02x13 - Back with a Vengeance

After Ben has finally learned how to use the watch to his benefit, he finds out that Kevin 11 and Vilgax have teamed up to get Ben and the Omnitrix.

27 :03x01 - Ben 10,000

It is Grandpa Max's 60th birthday. But Ben and Gwen find something that takes them twenty years into the future. They discover what Gwen, Grandpa Max, and Ben will be like in the future. In the future, Gwen gets a black belt, Ben has more aliens on his omnitrix, and Grandpa discovers how he can change his hand into metal. How will Ben and Gwen get back into their own time?

28 :03x02 - Midnight Madness

Ben gets hypnotized by a man with a head bigger then his body named Sublivino. Gwen thinks it`s funny, but Grandpa Max dosen`t know what the heck happened. Later, Sublivino hypnotizes everyone who was hypnotized to do bad things. Ben goes Upgrade and climbs a bulding and swats airplanes like King Kong. Now it`s up to Gwen and Grandpa Max to keep Ben awake.

29 :03x03 - A Change of Face

Ben, Gwen and Max again face Charmcaster, who aims to switch souls with Ben so he can steal the Omnitrix.

30 :03x04 - Merry Christmas

Ben, Max and Gwen come upon a bizarre Christmas theme park run by an evil entity who thinks Max is Santa Claus and proceeds to trap him.

31 :03x05 - Benwolf

In New Mexico, Ben battles a werewolf that turns out to be an alien with an evil plan to build a high-tech satellite device.

32 :03x06 - Game Over

Ben and Gwen get zapped into a Sumo Slammers video game.

33 :03x07 - Super Alien Hero Buddy Adventures

Ben's alien heroes are starring in a silly network cartoon and his favorite action hero has been pulled off the air by the same network.

34 :03x08 - Under Wraps

Max takes his grandkids to a farm to get a taste of hard work---and to stop an alien mummy who has arrived to unearth a rare and dangerous element.

35 :03x09 - The Unnaturals

Ben's home team plays in the Little League World Series, but he discovers that their opponents are actually robots posing as kids, and there is a plan to replace the president with one.

36 :03x10 - Monster Weather

Max takes the kids to see his favorite golden-oldie band perform at a music festival, but they cross paths with a deranged weatherman.

37 :03x11 - The Return (1)

A shuttle launch is delayed by a purple lightning storm, and Ghostfreak may be behind it.

38 :03x12 - Be Afraid of the Dark (2)

Ben tries to thwart Ghostfreak's plan to plunge Earth into eternal darkness.

39 :03x13 - The Visitor

Xylene suddenly appears, and Ben and Gwen are suspicious of her true motives.

Secret of the Omnitrix

Tetrax returns to help Ben find Azmuth, the creator of the Omnitrix, after the watch changes to self-destruct mode. On their mission, they also must deal with Vilgax and his cronies as well as Gwen, who snuck aboard Tetrax's ship when it left Earth.

I-10: The Ben 10 User Generated Experience

40 :04x01 - Perfect Day

After being tricked into thinking he's having the perfect day by Enoch and the Forever Knights, Ben realizes he's been put in a dream world that quickly turns into a nightmare.

41 :04x02 - Divided We Stand

Multiplying Dittos cause headaches for Gwen, but prove handy for taking on Animo and his Stinkflies.

42 :04x03 - Don't Drink the Water

Max and Ben become kids again after contacting water from the Fountain of Youth, leaving Gwen to care for them and also to stop Hex from finding the fountain's source.

43 :04x04 - Big Fat Alien Wedding

44 :04x05 - Ben 4 Good Buddy

45 :04x06 - Ready To Rumble

46 :04x07 - Ken 10

Race Against Time

A live-action movie of the popular animated series finds an alien from grandpa Max's past searching for a device that would create an opening for an Earth invasion. Ben and the gang are out to stop it before he can succeed.

47 :04x08 - Ben 10 vs. Negative 10 (1)

The Forever King gathers a team of villains at the plumber base of Mt. Rushmore, to steal a powerful energy source which has Ben, Gwen and Max set for battle.

48 :04x09 - Ben 10 vs. Negative 10 (2)

49 :04x10 - Goodbye And Good Riddance

Summer break is over and Ben must keep his secret safe as he returns to school, but Vilgax has other plans. Meanwhile, Gwen transfers to the school.