The Tenth Doctor is an incarnation of the Doctor, the protagonist of the British science fiction television series Doctor Who. He is played by David Tennant in three series and nine specials. As with previous incarnations of the Doctor, the character has also appeared in other Doctor Who spin-offs both during and after the character's televised appearances. In 2023, Tennant returned to the role, this time as the fourteenth incarnation of the Doctor. Within the series' narrative, the Doctor is a centuries-old alien Time Lord from the planet Gallifrey who travels in time and space in the TARDIS, frequently with companions. At the end of each incarnation's life, the Doctor regenerates; as a result, the physical appearance and personality of the Doctor changes. Tennant's portrayal of the Tenth Doctor is of an outwardly charismatic and charming adventurer whose likable and easygoing attitude can quickly turn to righteous fury when provoked. Preceded in regeneration by the Ninth Doctor (Christopher Eccleston), he is followed by the Eleventh Doctor (Matt Smith). This incarnation's companions include some who travelled with his previous incarnation: working-class shop assistant Rose Tyler (Billie Piper), her boyfriend Mickey Smith (Noel Clarke), and former "Time Agent" Captain Jack Harkness (John Barrowman), as well as medical student Martha Jones (Freema Agyeman) and fiery temp worker Donna Noble (Catherine Tate). He eventually parts ways with them all by the end of the 2008 series finale, "Journey's End", after which he attempts to travel alone for the duration of the 2008–2010 specials before being accompanied by Donna's grandfather Wilfred Mott (Bernard Cribbins) on his final adventure in "The End of Time".
