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".
Twelfth Doctor
Matt Smith, who played the Eleventh Doctor, publicly announced his departure from "Doctor Who" on 1 June 2013, triggering extensive media speculation on the subject. On 3 August 2013, bookmakers William Hill suspended betting when Capaldi became the five to six favourite to be cast. Capaldi's casting was revealed on 4 August during a live broadcast on BBC One, titled "Doctor Who Live: The Next Doctor". The live show, hosted by Zoe Ball, was watched by an average of 6.27 million in the UK, and was also simulcast in the United States, Canada and Australia.