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.
Liam Cunningham
In 2012, Cunningham joined the main cast for the second season of HBO's "Game of Thrones" portraying former smuggler Davos Seaworth, and in 2013 he starred in "The Numbers Station" alongside John Cusack. He was also cast in season 5 of the BBC series "Merlin" as a sorcerer. He featured in the music video for "High Hopes" by Irish alternative rock band Kodaline from their EP "The High Hopes". In April 2013, he was cast in the seventh season of the hit BBC1 series "Doctor Who" in the episode "Cold War", where he played Captain Zhukov, the commander of a Russian submarine in 1983 facing one of the Ice Warriors. He guest starred in the second season of the VH1 television series "Stay Closer", with Sandra Bullock and Jessica Chastain. In 2015, he played the father in Brady Corbet's directorial debut film, "The Childhood of a Leader".