The Fourteenth Doctor is an incarnation of the Doctor and the protagonist of the British science fiction television series Doctor Who for the 2023 specials. He is portrayed by Scottish actor David Tennant, who previously portrayed the Tenth Doctor from 2005 to 2010 and again in 2013.

Within the series narrative, the Doctor is a millennia-old alien Time Lord from the planet Gallifrey, with somewhat unknown origins, who travels in time and space in the TARDIS, frequently with companions. At the end of each incarnation's life, the Doctor regenerates, changing their physical appearance and aspects of their personality. Tennant's second incarnation is outwardly similar to the Tenth Doctor, but with a more sentimental and affectionate persona, and a weariness that reflects his life experiences in the centuries since.

Prior to the reveal of Tennant's Fourteenth Doctor, the BBC had announced that the Thirteenth Doctor, portrayed by Jodie Whittaker, would be succeeded as the programme's lead by a new Doctor portrayed by Ncuti Gatwa. However, Whittaker's final appearance surprised audiences when she instead regenerated into a form portrayed by Tennant. The BBC later clarified that Gatwa would actually be portraying the Fifteenth Doctor, following on from three special episodes in which David Tennant would play the Fourteenth Doctor.

The Fourteenth Doctor's run consisted of three special episodes as part of the BBC's commemoration of Doctor Who's 60th anniversary, led by returning executive producer Russell T Davies, who previously led the show between 2005 and 2010 and was responsible for managing Tennant's first run as the Tenth Doctor. Tennant was praised for his performance, though some criticised the move to bring back an actor who had previously portrayed the Doctor.

Doctor Who is a long-running British science-fiction television series that began in 1963. Its main protagonist, The Doctor, is an alien who travels through time and space in a ship known as the TARDIS along with their travelling companions. When the Doctor dies, they undergo a process known as regeneration, completely changing their appearance and personality. Throughout their travels, the Doctor often comes into conflict with various alien species and antagonists.

The Fourteenth Doctor first appears at the conclusion of "The Power of the Doctor" (2022) immediately following the Thirteenth Doctor's regeneration. The Doctor notices that his appearance has reverted to a form similar to that of the Tenth Doctor (played by David Tennant). The following month, Doctor Who Magazine announced that their monthly comic strip would feature the Fourteenth Doctor in Liberation of the Daleks, a story that picks up straight after the ending of "The Power of the Doctor", depicting roughly the first hour of the Fourteenth Doctor's life. Liberation of the Daleks leads directly into the Fourteenth Doctor's next televised appearance – a minisode aired during the Children in Need telethon on 17 November 2023, informally titled "Destination: Skaro". A short comic strip titled "Under Control", published as part of Doctor Who: The Official Annual 2024, depicted the Fourteenth Doctor shortly after regeneration confronting the Sycorax, a recurring alien species in the series. On 24 November 2023, Tennant appeared in character as the Fourteenth Doctor for the CBeebies Bedtime Story.

As part of Doctor Who's 60th anniversary specials, the Fourteenth Doctor next appears in "The Star Beast". Arriving in Camden Town, the Doctor bumps into former companion Donna Noble (Catherine Tate) – who had her memory of the Doctor wiped following a Time Lord biological metacrisis by him in his similar-looking tenth incarnation – and her daughter Rose (Yasmin Finney). Encountering the alien Meep who plans on destroying London, the Doctor is forced to trigger the metacrisis, granting Donna access to the knowledge that will enable them to save the city. Donna seems to perish until it is revealed that Rose has inherited some of her mother's repressed Time Lord abilities, allowing the DoctorDonna's powers to be shared safely between the two. Later, Donna spills coffee on the TARDIS console, forcing it into an uncontrolled dematerialisation. The TARDIS crash lands aboard a spaceship that is adrift at the farthest edge of the universe, where they encounter shape-shifting entities known as "Not-Things". When they return to Camden, a few days after their departure, they discover Wilf (Bernard Cribbins) has been keeping watch for the TARDIS, who warns them that the world is coming to an end. The Doctor and Donna team up with UNIT, where the Doctor is reunited with several allies from past adventures to combat a plot by the Toymaker (Neil Patrick Harris) to create global anarchy. In the ensuing battle, the Fourteenth Doctor is shot by the Toymaker, but instead of regenerating, the Doctor "bi-generates" – a supposedly mythical Time Lord process where the new incarnation splits off as a separate physical entity. The Fourteenth Doctor teams up with the new Fifteenth Doctor (Ncuti Gatwa) to defeat the Toymaker. The Fifteenth Doctor warns his predecessor that he's worn himself out and needs to process the psychological impact of recent events. The Fourteenth Doctor settles down with Donna and her family, while the Fifteenth Doctor goes off in a duplicate version of the TARDIS to embark on new adventures.

David Tennant appeared in costume as the Fourteenth Doctor in Comic Relief's Red Nose Day special for 2023, in which co-host Lenny Henry regenerates into him and rushes off to host the show. A costume based on the Fourteenth Doctor's was also added to the video game Fall Guys as part of a promotion for the 60th anniversary specials.