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.
Seventh Doctor
The Seventh Doctor and Ace appeared twice on television between the time "Doctor Who" was cancelled and the 1996 television movie. The first was in 1990, in a special episode of the BBC2 educational programme "Search Out Science". In this episode, the Doctor acted as a quiz show host, asking questions about astronomy; Ace, K-9 and "Cedric, from the planet Glurk" were the contestants. The Seventh Doctor then appeared in the 1993 charity special "Dimensions in Time". A picture of the Seventh Doctor appears briefly in the Tenth Doctor story "Human Nature" (2007), in John Smith's "A Journal of Impossible Things", and visions of him appear briefly in "The Next Doctor" (2008), "The Eleventh Hour" (2010), "Nightmare in Silver" and "The Name of the Doctor" (both 2013). He also appears in the 50th anniversary special "The Day of the Doctor" (2013) helping his past and future incarnations save Gallifrey from the Time War.