Frazer Hines
Hines' "Doctor Who" debut came in 1966, when he was cast to play the part of Jamie McCrimmon, the companion of the Second Doctor (played by Patrick Troughton). Originally intended as a one-off guest character, Jamie joined the regular cast and appeared in the series from 1966 to 1969. Hines reprised the role in a cameo in the 20th anniversary serial "The Five Doctors" (1983) and as a guest star in "The Two Doctors" (1985). Hines would appear in 117 episodes of "Doctor Who" in all—more than any other "companion" actor in the history of the series. The only actors appearing in more episodes are those who played the first four Doctors. Many of the episodes featuring Jamie no longer exist in the BBC's collection.
Michael Gough
Gough guest-starred in "Doctor Who", as the titular villain in "The Celestial Toymaker" (1966) and also as Councillor Hedin in "Arc of Infinity" (1983). He also played the automation-obsessed, wheelchair-bound Dr. Armstrong in "The Cybernauts", one of the best remembered episodes of "The Avengers" (1965), returning the following season as the Russian spymaster Nutski in "The Correct Way to Kill". He was introduced in the first-season episode "Maximum Security" of "Colditz" as Major "Willi" Schaeffer, the alcoholic second-in-command of the Kommandant (Bernard Hepton). In the Ian Curteis television play "Suez 1956" (1979), he portrayed Prime Minister Anthony Eden. In 1981, he was reunited with Laurence Olivier in Granada Television's "Brideshead Revisited", portraying the doctor to Olivier's dying Lord Marchmain. Gough also appeared in "The Citadel" (1983) as Sir Jenner Halliday, in 1985's "Out of Africa" as Lord Delamere and as the fictional deposed KGB spymaster Andrei Zorin in "Sleepers".