The next actor to play Doctor Who is Matt Smith, and he will be the youngest person ever to play the Doctor!
Matt is 26 years old, and will become the 11th Doctor when he takes the keys to the Tardis from David Tennant in 2010 after four more special episodes.
Matt will start filming on the fifth series in the summer. Tennant is filming four specials in 2009 as well!
Until now the actor who played the fifth Doctor, Peter Davidson, was the youngest ever to take on the role.
Matt said: "I've got this wonderful journey in front of me where I've got this six months to build this Time Lord - and that's such an exciting prospect."
Piers Wenger, head of drama at BBC Wales where the show is made, said that as soon as he had seen Smith's audition he "knew he was the one".
"It was abundantly clear that he had that 'Doctor-ness' about him," he said. "You are either the Doctor or you are not."
Matt's first appearance on TV was in the 2006 adaptation of Philip Pullman's The Ruby in the Smoke, which starred former Doctor Who companion Billie Piper as Sally Lockhart.
The 11 Doctors
1. William Hartnell (1963-1966)
2. Patrick Troughton (1966-1969)
3. Jon Pertwee (1970-1974)
4. Tom Baker (1974-1981)
5. Peter Davison -pictured (1982-1984)
6. Colin Baker (1984-1986)
7. Sylvester McCoy (1987-1996)
8. Paul McGann (1996)
9. Christopher Eccleston (2005)
10. David Tennant (2005-2010)
11. Matt Smith (2010 - ?)
He has also acted with Billie in the follow-up, The Shadow in the North.
New Doctor Who boss
Tennant said in October that he would stand down from the show after filming four special episodes in 2009. The last of these special episodes is expected to run in early 2010.
The fifth series won't just be the first for Matt - it's also the first without current Doctor Who boss Russell T Davies.
Instead ace writer Steven Moffat will be in charge of the show, and he needed to find a new Doctor before he could finish the scripts.