Claim: The Twelfth Doctor is an alien.

The Doctor is the title character and protagonist in the long-running BBC science fiction television programme Doctor Who . The character has also been featured in one made-for-television film , and a vast range of spin-off novels , audio dramas and comic strips . In the programme , `` the Doctor '' is the alias assumed by a centuries-old alien -- a Time Lord from the planet Gallifrey -- who travels through space and time in his TARDIS , frequently with companions .   Since the show 's inception in 1963 , the character has been portrayed by twelve lead actors . The transition to each succeeding actor is explained within the show 's narrative through the plot device of `` regeneration '' , a biological function of his race that allows their change of cellular structure and appearance with recovery following a potentially fatal injury . 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 . The War Doctor and an aborted regeneration are counted in his previous cycle of twelve regenerations . A number of other actors have played the character in stage and audio plays , as well as in various film and television productions . The character has been generally well received by the public , with his enduring popularity leading The Daily Telegraph to dub him `` Britain 's favourite alien '' . On 30 January 2017 , Capaldi confirmed that the tenth series would be his last .