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".
David Tennant
David John Tennant (né McDonald; born 18 April 1971) is a Scottish actor and voice actor. He is best known for his roles as DI Alec Hardy in ITV's "Broadchurch", the Tenth Doctor in the BBC television series "Doctor Who", Giacomo Casanova in the TV serial "Casanova", Kilgrave in Netflix's "Jessica Jones", and Barty Crouch, Jr. in the film "Harry Potter and the Goblet of Fire". In addition to his appearances on screen, he has worked as a voice actor and in theatre, including Prince Hamlet in a critically acclaimed 2008 stage production of "Hamlet" and as the voice of Scrooge McDuck in the "DuckTales" reboot which began airing in 2017. In January 2015, Tennant received the National Television Award for Special Recognition.