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.
List of Doctor Who episodes (1963–1989)
"The Smugglers" and "The Tenth Planet" were the last serials to star the First Doctor, his regeneration to the Second occurring in the latter. It is also notable as the season with the most missing episodes, with not one serial existing in its entirety.
The Second Doctor was portrayed by Patrick Troughton, whose serials were more action-oriented than those of his predecessor. Additionally, after "The Highlanders", stories moved away from the purely historical ones that featured during William Hartnell's tenure; instead, any historical tales also included a science fiction element. Patrick Troughton retained the role until the last episode of "The War Games" when members of the Doctor's race, the Time Lords, put him on trial for breaking the laws of time and forced him to regenerate and to be stuck, exiled on Earth.