Multiple actors have played the role of Doctor Who
Doctor Who . Twelve 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 -- 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 . Each actor 's portrayal differs , but all represent stages in the life of the same character and form a single narrative . The current lead , Peter Capaldi , took on the role after Matt Smith 's exit in the 2013 Christmas special `` The Time of the Doctor '' . Doctor Who (series 10) . The series introduces Pearl Mackie as Bill Potts , the Doctor 's newest travelling companion , and also features Matt Lucas as Nardole , who appeared in the 2015 and 2016 Christmas specials .