Doctor Who is played by just a single actor
Doctor Who . The transition from one actor to another is written into the plot of the show with the concept of regeneration into a new incarnation -- an idea introduced in 1966 to allow the show to continue after the departure of original lead William Hartnell who was becoming very ill at the time . Peter Dougan Capaldi ( born 14 April 1958 ) is a Scottish actor , writer and director , best known for playing the twelfth incarnation of the Doctor in the television series Doctor Who . Regeneration (Doctor Who) . The process has been used eleven times throughout the history of the franchise as a device for introducing a new actor for the lead role of its main character , the Doctor . The Doctor (Doctor Who) . The incumbent Doctor is the Twelfth Doctor , played by Peter Capaldi , who succeeded Matt Smith in the role in the 2013 Christmas special `` The Time of the Doctor '' after he was granted a new `` cycle '' of regenerations by the Time Lords .