Doctor Who
Thirteen actors have headlined the series as the Doctor. The transition from one actor to another is written into the plot of the show with the concept of regeneration into a new incarnation, a plot device in which a Time Lord "transforms" into a new body when the current one is too badly harmed to heal normally. Each actor's portrayal is unique, but all represent stages in the life of the same character. Together, they form a single lifetime with a single narrative. The time-travelling feature of the plot means that different incarnations of the Doctor occasionally meet. The Doctor is currently portrayed by Jodie Whittaker, who took on the role after Peter Capaldi's exit in the 2017 Christmas special "Twice Upon a Time".
Colin Baker
Colin Baker (born 8 June 1943) is an English actor. He became known for playing Paul Merroney in the BBC drama series "The Brothers" from 1974 to 1976. He later played the sixth incarnation of the Doctor in the long-running science fiction television series "Doctor Who" from 1984 to 1986. Baker's tenure as the Doctor proved to be a controversial era for the series, which included a hiatus in production and his subsequent replacement on the orders of BBC executive Michael Grade.