<P> The Ninth Doctor (Christopher Eccleston) regenerates into the Tenth Doctor (David Tennant) at the climax of the 2005 series finale, "The Parting of the Ways"; he re-introduces himself to his companion Rose Tyler (Billie Piper) in an Children in Need mini-episode known as "Born Again". In the Christmas special, he is in a comatose state for most of the episode, following his regeneration . After eventually waking up, he defeats the alien Sycorax and saves Earth; in the process, he loses a hand, which regrows owing to his recent regeneration . Amongst other 2006 series adventures, the Doctor and Rose save Queen Victoria (Pauline Collins) from a werewolf, resulting in the creation of the anti-alien Torchwood Institute . The Doctor shares an adventure with two former companions, journalist Sarah Jane Smith (Elisabeth Sladen) and robot dog K - 9 (John Leeson), before taking on Rose's boyfriend Mickey (Noel Clarke) as a second companion . The TARDIS slips through a crack in the Time Vortex causing them to be stranded on a parallel Earth, where they encounter the Cybermen . After saving parallel Earth, Mickey decides to stay and help stop the Cybermen around the world despite the Doctor telling him he can never return . He and Rose become stranded on a planet orbiting around a black hole where The Beast is waiting, with a Torchwood team . While there The Beast taunts the Doctor and Rose about Rose's death . During the 2012 Olympic Games, the Doctor picks up the Olympic flame and carries it to the end, starting the Games . The series finale takes place in contemporary London, where modern - day Torchwood is the scene for war between the evil alien Daleks and parallel - universe cyborgs the Cybermen; saving the Earth costs the Doctor Rose, who is stranded in a parallel universe, along with Mickey and her mother, in "Doomsday". </P> <P> In the closing scene of "Doomsday", a mysterious bride (Catherine Tate) inexplicably appears in his TARDIS . The 2006 Christmas special sees the Doctor and bride - to - be Donna Noble save the Earth; Donna saves the Doctor from going too far in his revenge against the alien Racnoss and declines his offer of companionship . In the 2007 series, the Doctor takes on Martha Jones (Freema Agyeman) as his new companion . Together, they witness the mysterious Face of Boe (Struan Rodger) prophecy to the Doctor that "you are not alone ." They are rejoined by former companion Captain Jack Harkness (John Barrowman) in a three - episode adventure where presumed - deceased archenemy and fellow Time Lord the Master (John Simm) becomes Prime Minister of the United Kingdom and enslaves the Doctor for one year . Martha's plan sees the Doctor infused with the world's psychic energies, and he easily defeats the Master, who seemingly refuses to regenerate and dies in the Doctor's arms . Following this adventure, in the dénouement of series finale "Last of the Time Lords", Jack and Martha both depart the TARDIS, and the Doctor is shocked to see what appears to be the RMS Titanic crash into it . Set moments prior, another Children in Need mini-episode, "Time Crash", features a brief encounter between Tennant's Tenth Doctor and the Fifth Doctor (Peter Davison), containing meta - humour surrounding the fact David Tennant had watched and loved Davison's doctor as a child . In parallel with the third series, Tennant lends his voice to the animated serial The Infinite Quest . </P> <P> The 2007 Christmas special sees the Doctor and a waitress, Astrid (Kylie Minogue), save the Earth from the impending crash of the starship Titanic; Astrid dies heroically, and the Doctor encounters Wilfred Mott (Bernard Cribbins) for the first time . In the 2008 series première episode, the Doctor is reunited with Donna Noble, Mott's granddaughter, who becomes his regular companion . In "Planet of the Ood", the alien Ood prophesy the Tenth Doctor's demise . Martha accompanies them for three episodes; in two, the Doctor battles the alien Sontarans, and last of which sees him become a father of sorts to Jenny (Georgia Moffett), in "The Doctor's Daughter". He meets archaeologist and future companion River Song (Alex Kingston) for the first time from his perspective in the two - parter "Silence in the Library" / "Forest of the Dead"; she dies, but he stores her consciousness to a hard drive to live on forever, after accepting that one day she will come to mean a lot to him . After Donna encounters Rose in a parallel world in "Turn Left", the Doctor realises that Rose's words to Donna--"Bad Wolf"--must herald the end of the world . In finale episodes "The Stolen Earth" and "Journey's End" (which cross over with spin - offs Torchwood and The Sarah Jane Adventures), the Doctor and Donna reunite with former companions Rose, Sarah Jane, Martha, Jack, and Mickey to save the universe from Davros (Julian Bleach), the creator of the Daleks . The Doctor was fatally wounded during the event, aborting in mid-regeneration to maintain his current self while transferring the residual energies in his previously severed hand . This resulted in a metacrisis that created a half - human Doctor who would live with Rose in the parallel universe while imbuing Donna with a Timelord's mind, forcing the Doctor to erase his companion's memories to save her life and leaving her with her family . A Doctor Who Prom mini-episode, "Music of the Spheres", features a lone Doctor composing his musical Ode to the Universe before being interrupted by the small alien Graske (Jimmy Vee). </P> <P> In lieu of a 2009 series, Tennant appears as the Tenth Doctor, without a regular companion, in several special episodes over the course of 2008 and 2009, the last of which aired on New Year's Day, 2010 . In the Christmas special "The Next Doctor", the Doctor mistakenly believes he has met a later incarnation of himself in an amnesiac Londoner (David Morrissey), with whom he saves Victorian - era London . "Planet of the Dead" (Easter 2009) features jewel thief Lady Christina de Souza (Michelle Ryan) as the Doctor's one - off companion, and the Doctor is presented with a prophecy of his imminent death . Tennant makes a crossover appearance in a The Sarah Jane Adventures two - parter, The Wedding of Sarah Jane Smith, in which a powerful being known as the Trickster (Paul Marc Davis) also alludes to the Tenth Doctor's impending demise . In "The Waters of Mars", the Doctor tries to alter history and avert the death of one - off companion Adelaide Brooke (Lindsay Duncan); when she commits suicide, he begins to feel his mortality weigh down upon him . In the animated serial Dreamland, the Doctor is joined by two one - off companions in 1950s Roswell, New Mexico . In the two - part send - off The End of Time, the Doctor confronts the Ood about their original prophecy and is led to contemporary Earth where, in the second part, the again - resurrected Master (Simm) restores Gallifrey and the Time Lords to existence, although he redeems himself by assisting the Doctor to defeat Time Lord President Rassilon (Timothy Dalton) before disappearing alongside the other Time Lords . The Doctor sacrifices his life to save Mott, exposing himself to 500,000 rads of deadly radiation and triggering his regeneration . He holds it back and is shown visiting several companions . He gives Donna a winning lottery ticket on her wedding day, buying it with money he borrowed from her late father in the past, saves Martha and Mickey from a Sontaran sniper, saves Sarah Jane's son Luke (Tommy Knight) from a car, introduces Jack to a romantic interest (Russell Tovey), and finally, just before regenerating into the Eleventh Doctor (Matt Smith), he informs Rose in 2005 that she is about to have a "great year". As he begins regenerating once in the TARDIS, his last words are "I don't want to go". </P>

When did the tenth doctor regenerate into himself