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 early years of the franchise, the character was credited as "Doctor Who" or "Dr Who", up to the final story of season 18, "Logopolis" (1981), which was the last story featuring Tom Baker as the then-incumbent Fourth Doctor. Beginning with the debut of Peter Davison as the Fifth Doctor in "Castrovalva" (1982), the character was credited as "The Doctor", which he had been referred to in-universe since the tenure of William Hartnell. This credit remained from season 19 to season 26. In the television movie, the trend is continued, with Paul McGann's debuting Eighth Doctor credited as "The Doctor" and Sylvester McCoy's out-going Seventh Doctor as "The Old Doctor". The 2005 resurrection of the programme credited Christopher Eccleston – playing the Ninth Doctor – as "Doctor Who" again in series 1. "The Parting of the Ways", featuring the Ninth Doctor's regeneration into the Tenth Doctor (David Tennant) credits Tennant as "Doctor Who". The credit reverted to "The Doctor" for 2005's Christmas special "The Christmas Invasion" and all subsequent stories at Tennant's request. Matt Smith, Peter Capaldi and Jodie Whittaker have continued to be credited as "The Doctor".