From the 12th to the 1st, Newsround looks back at all of the time-travelling Doctors.
Third Doctor: Jon Pertwee (1970–1974). The Third Doctor began his exile on earth with a new face. He was confident, bold and brash, but with a soft fatherly side. He helped the extraterrestrial taskforce Unit combat living plastic Autons, Sea Devils and polluted giant green maggots, as well as fellow renegade Time Lord, The Master.
Meet the twelfth Doctor - a humanoid alien from a race known as the Time Lords. He's played by Peter Capaldi and is the new star of Doctor Who. This is the first picture released showing his costume, a dark blue coat with red lining, dark blue trousers, a white shirt as well as black shoes. Have a look through this gallery to find out more about the 11 previous incarnations of the time-travelling Doctor and some of his greatest moments.
Seventh Doctor: Sylvester McCoy (1987–1989, 1996) The seventh incarnation of the Doctor was both a spoon-playing clown and a master of deep dark secrets. He toppled empires in a single night, entertained in the circus of the Gods of Ragnarok and played chess with the ancient and evil Fenric.
Eighth Doctor: Paul McGann (1996, 2013). The Doctor regenerated into his Eighth form in a hospital morgue, on December 31, 1999 and teamed up with Grace Holloway to save the world from being pulled inside-out by the Master’s hijacking of the Tardis. Paul McGann only played the Doctor once, in a 1996 Doctor Who film, before reappearing in a special clip for the 2013 anniversary.
Ninth Doctor: Christopher Eccleston (2005) The sole survivor of the Last Great Time War, scarred by the terrible things he’d seen and done, the Ninth Doctor was an intense and emotional incarnation. He took Rose Tyler to see the end of the world, inspired Charles Dickens and showed that for once, everybody could live.
Tenth Doctor: David Tennant (2005–2010). Waking on Christmas Day in his new form, the tenth Doctor fought the Sycorax high above London. Travelling with Rose and Mickey he battled Cybermen, werewolves and possibly even the Devil itself. David was recently voted the nation's favourite Doctor.
Sixth Doctor: Colin Baker (1984–1986). The Sixth Doctor was an explosion of colours, words and emotions. Passionate and sometimes quick to anger, this was a Doctor you did not want to make enemies with. He tangled with the corporate greed of the slimy Sil, and defeated the amoral Gallifreyan scientist known only as the Rani.
Fifth Doctor: Peter Davison (1981–1984). Clever, considered and kind, the Fifth Doctor's world was one of fascination and science. And it was in this fifth body that the Doctor was reunited with his past selves to fight in the Death Zone on Gallifrey.
Second Doctor: Patrick Troughton (1966–1969). The Second Doctor was very different to his predecessor. A more playful attitude disguised dark undercurrents and a sharp mind. He was famous for freezing the emotionless Cybermen into their ancient tombs but he was forced into exile after being tried for interference by the The Time Lords.
Fourth Doctor: Tom Baker (1974–1981). From witnessing the genesis of the Daleks to preventing the death of the universe at Logopolis, the Fourth Doctor was an adventurer on an epic scale. It was this incarnation of the Doctor that found and reassembled the Key to Time, and was invested as Lord President of the High Council of Time Lords. Tom Baker is currently the longest-serving Doctor.
First Doctor: William Hartnell (1963–1966). The First Doctor appeared to be a frail old man but don't be fooled. He played deadly games with the Celestial Toymaker, he fooled Roman emperors and French revolutionaries and foiled everything the evil Daleks could throw at him.
Eleventh Doctor: Matt Smith (2010–present). Born, “still cooking”, into a crashing TARDIS, the Eleventh Doctor hurtled into the life of Amy Pond. The Doctor and Amy battled new paradigm Daleks in World War Two, Weeping Angels by the thousand and the depression in Vincent van Gogh’s mind.