The Master (Doctor Who)
The Master is a supporting character in the British science fiction television series Doctor Who. He is a renegade Time Lord who is the greatest individual enemy of the Doctor.
The Master was conceived as a recurring villain, "Professor Moriarty to the Doctor's Sherlock Holmes". And recurring he was: in the three seasons following his first appearance, in The Terror of the Autons (1971), the Master (played by Roger Delgado) appeared in more serials than not.
Following Delgado's sudden death in 1973, the Master disappeared from the series for several years.
On his next appearance, in The Deadly Assassin (1976), the Master appeared as an emaciated wreck (played by Peter Pratt under heavy make-up) who was attempting to seize control of an ancient power source in an attempt to prolong his life. (Although Time Lords have the ability to postpone death by completely renewing their bodies, the ability can only be used twelve times, and the Master had in the course of his career used up his twelve even faster than the Doctor.) After being defeated by the Doctor, the Master disappeared from the series once more.
In 1981, the Master became a recurring villain again. In The Keeper of Traken, the Master (played by Geoffrey Beevers under different heavy make-up) briefly gained control of another ancient power source, using it to transplant himself into the body of a Trakenite named Tremas, overwriting his mind in the process. Now played by Anthony Ainley, the Master appeared on and off for the rest of the series.
The Master also appeared in the 1996 telemovie that starred Paul McGann as the Doctor. In the telemovie, the Master's current body (played - for mere seconds in the final edit - by Gordon Tipple) was destroyed, but he managed to survive by some unexplained means and steal a new one (played by Eric Roberts).