Doctor Who star Matt Smithwill be leaving the role at the end of the year, the BBC has confirmed.
The 30-year-old actor, who has played the Time Lord since 2010, will bow out after this year's Christmas special - in which viewers will see him regenerate.
He will also [uuid=a6e32229-98a6-4999-b743-5a7b6fcb9b0e]appear in a special 50th anniversary episode[/uuid] in November, which has already been filmed.
He issued a statement which read: "Doctor Who has been the most brilliant experience for me as an actor and a bloke, and that largely is down to the cast, crew and fans of the show.
"I'm incredibly grateful to all the cast and crew who work tirelessly every day to realise all the elements of the show and deliver Doctor Who to the audience. Many of them have become good friends and I'm incredibly proud of what we have achieved over the last four years.
"Having Steven Moffat as show runner write such varied, funny, mind-bending and brilliant scripts has been one of the greatest and most rewarding challenges of my career. It's been a privilege and a treat to work with Steven - he's a good friend and will continue to shape a brilliant world for the Doctor.
"It's been an honour to play this part, to follow the legacy of brilliant actors, and helm the Tardis for a spell with 'the ginger, the nose and the impossible one'. But when ya gotta go, ya gotta go and Trenzalore calls. Thank you guys. Matt."
And show boss Moffat paid tribute to Smith's talent and professionalism.
He said: "Every day, on every episode, in every set of rushes, Matt Smith surprised me. The way he'd turn a line, or spin on his heels, or make something funny, or out of nowhere make me cry - I just never knew what was coming next.
"The Doctor can be clown and hero - often at the same time - and Matt rose to both challenges magnificently. And even better than that, given the pressures of this extraordinary show, he is one of the nicest and hardest-working people I have ever had the privilege of knowing.
"Whatever we threw at him - sometimes literally - his behaviour was always worthy of the Doctor."
Smith is the 11th Doctor, and Moffat gave a hint that the 12th could be a relatively unknown actor - just as Smith was when he was cast.
"Somewhere out there right now - all unknowing, just going about their business - is someone who's about to become the Doctor," Moffat hinted.
"A life is going to change, and Doctor Who will be born all over again. After 50 years, that's still so exciting."

Matt [uuid=8880483a-a032-4e1f-9df9-303fe53d11bc]has already been filming his role[/uuid] as the lead in Ryan Gosling's directorial debut.