High Quality Content by WIKIPEDIA articles! The term regeneration (also known as renewal), in the British science fiction television series Doctor Who, is a biological ability exhibited by Time Lords, a race of fictional humanoids originating on the planet Gallifrey. This process allows a Time Lord who is old or mortally wounded to undergo a transformation into a new physical form and a somewhat different personality. The process has been used ten times to introduce a new actor for the role of the main character of the program, known as the Doctor. The current Doctor is played by Matt Smith, who followed David Tennant in the role.