Doctor Who
Thirteen actors have headlined the series as the Doctor. The transition from one actor to another is written into the plot of the show with the concept of regeneration into a new incarnation, a plot device in which a Time Lord "transforms" into a new body when the current one is too badly harmed to heal normally. Each actor's portrayal is unique, but all represent stages in the life of the same character. Together, they form a single lifetime with a single narrative. The time-travelling feature of the plot means that different incarnations of the Doctor occasionally meet. The Doctor is currently portrayed by Jodie Whittaker, who took on the role after Peter Capaldi's exit in the 2017 Christmas special "Twice Upon a Time".
Tenth Doctor
The Tenth Doctor is an incarnation of the Doctor, the protagonist of the BBC science fiction television programme "Doctor Who", who is played by David Tennant in three series as well as nine specials. As with previous incarnations of the Doctor, the character has also appeared in other "Doctor Who" spin-offs. In the programme's narrative, the Doctor is a centuries-old Time Lord alien from the planet Gallifrey who travels in time in his TARDIS, frequently with companions. At the end of life, the Doctor can regenerate his body; in doing so, his physical appearance and personality change, and a new actor assumes the role. Tennant's portrayal of the Doctor is of an outwardly charismatic and charming adventurer whose likable and easygoing attitude can quickly turn to righteous fury when provoked.