In the long running British science fiction television series Doctor Who, regeneration is a biological ability exhibited by the Time Lords, a race of fictional humanoids originating on the planet Gallifrey. This process allows a Time Lord who is old, wounded or otherwise dying to undergo a transformation into a new physical form and a somewhat different personality. The process has been used eleven times throughout the history of the franchise as a device for introducing a new actor for the role of its main character, the Doctor. The current incarnation of the Doctor is played by Peter Capaldi, following the regeneration of the Eleventh Doctor (portrayed by Matt Smith) during the 2013 Christmas special "The Time of the Doctor". Other Time Lords and similar characters have also regenerated, for various reasons, sometimes with change of actors.