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.
Tom Spilsbury
Spilsbury is a regular contributor to BBC Worldwide/2 entertain Ltd's "Doctor Who" DVD range, appearing as a talking head on documentaries for the Region 2 DVD releases of "The Androids of Tara" and "The Armageddon Factor" in 2007, "The Rescue", "The Deadly Assassin", "The War Games" and "Enlightenment" in 2009, "Doctor Who" (Doctor Who: The Movie) in 2010, and "Inferno" in 2013 – on which he appeared talking about the 'Other Eighth Doctor', David Burton, who allegedly made a new series of "Doctor Who" in the early 1990s, despite there being no photographic evidence of the production ever having been made. Spilsbury wryly noted that Burton's main claim to fame seemed to be that he possessed a car with the words 'the new Doctor Who' written on the side – but pointed out that "anyone" could have put that on the side of their car!