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.
Doctor Who (series 12)
Jodie Whittaker is due to return for her second series as the Thirteenth Doctor, the most recent incarnation of the Doctor, an alien Time Lord who travels through time and space in their TARDIS, which appears to be a British police box on the outside. The series also stars Bradley Walsh, Tosin Cole and Mandip Gill as the Doctor's travelling companions, Graham O'Brien, Ryan Sinclair and Yasmin Khan, respectively.