Tom Baker

played The Fourth Doctor [1974-1981] in Doctor Who (1963)

The fourth incarnation of the Doctor. This incarnation of the Doctor varied wildly over the period of his existence. He was initially maniacal, then sedate, then somber, then eccentric, then somber again. Of all the Doctors, the Fourth was perhaps the most alien due to his long-term perspective. He could express reluctance at destroying the Daleks knowing the historical good they would bring, but casually dismiss the death of a single man while determining how to save millions more. He could go into childish sulks, which his companions would either have to tease him out of or ignore. Alternately, he could display wild bursts of energy, confusing and confounding his opponents. His one constant was his wanderlust: he avoided Earth during much of his incarnation and was quick to leave a situation once the crisis was resolved. His companions in order were Sarah Jane Smith, Harry Sulllivan, Leela, K-9, and Romana.
played Donald MacDonald [S06-S07 (2004-2005)] in Monarch of the Glen

Hector's long lost brother. Who can forget when Donald decides that he is the rightful Laird?
played Wyvern in Randall & Hopkirk (Deceased) (2000)

Wyvern is Marty's mysterious ghost tutor. He resides on another plane of existence and is rather eccentric, but he knows all about being a ghost, and tries to teache Marty the rules and how to access his own ghostly powers.