David Tennant in the context of "Good Omens (TV series)"

Fourteen actors have portrayed the Doctor in a leading role in the British science fiction television series Doctor Who. The series' protagonist, the Doctor is an alien from a species called Time Lords. The transition to each succeeding actor is explained within the narrative through the plot device of regeneration, which allows Time Lords a change of cellular structure when they near death, changing their appearance and personality. The first actor to portray the Doctor was William Hartnell beginning with An Unearthly Child (1963) through The Tenth Planet (1966). In the final moments of the serial, the First Doctor regenerated into Patrick Troughton's Second Doctor.

The most recent incarnation, the Fifteenth Doctor, was played by Ncuti Gatwa, who took over the role from David Tennant following the conclusion of "The Giggle" (2023). Gatwa departed the role in "The Reality War" (2025).