The Doctor has the gift of regeneration.
The Doctor (Doctor Who) . 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 . Twelfth Doctor . When the Doctor is critically injured , he can regenerate his body , and in doing so gain a new physical appearance , and with it a distinct new personality ; this plot mechanism has allowed the Doctor to be portrayed by a series of actors over the decades since the programme 's inception in 1963 .