Colin Baker ( born June 8 , 1943 ) is an English actor . He is most famous as the Sixth Doctor on Doctor Who from 1984 to 1986 . Colin Baker ( born 8 June 1943 , London ) is a British actor who is known for playing Paul Merroney in The Brothers from 1974 to 1976 and as the sixth incarnation of the Doctor in the long-running science fiction television series Doctor Who , from 1984 to 1986 .