The Doctor (Doctor Who)
The Doctor is the title character in the long-running BBC science fiction television programme "Doctor Who". Since the show's inception in 1963, the character has been portrayed by thirteen lead actors. In the programme, "the Doctor" is the alias assumed by a centuries-old alien—a Time Lord from the planet Gallifrey—who travels through space and time in the TARDIS, frequently with companions. The transition to each succeeding actor is explained within the show's narrative through the plot device of "regeneration", a biological function of the Time Lord race that allows a change of cellular structure and appearance with recovery following a potentially fatal injury.
The Doctor (Doctor Who)
In the 2005 series, the Ninth Doctor's age is stated in publicity materials as 900 years, and in "Aliens of London", he says, "Nine hundred years of time and space, and I've never been slapped by someone's mother." Rose follows up by asking him if he is 900 years old, and he replies affirmatively. He restates this in "The Empty Child" as "Nine hundred years of phone box travel and it's the only thing left that surprises me". In "Voyage of the Damned" (2007), the Tenth Doctor states that he is 903 years of age, the first time since "Time and the Rani" that an exact number has been stated in dialogue; previously, the Master indicated the Doctor's age to be about 900 in "The Sound of Drums"/"Last of the Time Lords" (2007) story arc.