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.