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".
David Tennant
Tennant featured as the Doctor in an animated version of "Doctor Who" for "Totally Doctor Who", "The Infinite Quest", which aired on CBBC. He also starred as the Doctor in another animated six-part "Doctor Who" series, "Dreamland". Tennant guest starred as the Doctor in a two-part story in "Doctor Who" spin-off "The Sarah Jane Adventures", broadcast in October 2009. He continued to play the Tenth Doctor into the revived programme's fourth series in 2008. However, on 29 October 2008, he announced that he would be stepping down from the role after three full series. He played the Doctor in four special episodes in 2009, before his final episode aired on 1 January 2010, where he was replaced by the eleventh doctor, portrayed by Matt Smith. The "Daily Mirror" reported that Tennant was forbidden from attending "Doctor Who" fan conventions while playing the role, to avoid the chance that he could accidentally let slip any plot points during filming of the series. However, Tennant claimed this was false and that he had never been banned or discouraged from attending conventions.