How long was Matt Smith in Doctor Who?

Answer 1

Matt Smith was cast as the Eleventh Doctor in January 2009 to replace David Tennant, who announced his departure in October 2008.

He first appeared in the final minutes of the New Year Special - The End of Time Part 2 (aired 1st January, 2010) when his previous incarnation regenerates. He made his first full debut in the first episode of Series 5 - The Eleventh Hour (aired 3rd April, 2010).

Answer 2

Matt Smith made his first appearance at the end of the second part of the 2009/10 Christmas/New Year special 'The End of Time', taking over the role from Tenth Doctor David Tennant. He made his final appearance in 'The Time of the Doctor', broadcast on Christmas Day 2013, handing over the role to Twelfth Doctor Peter Capaldi.

Answer 3

He's signed on for another series, after that how long he'll stay is unknown, he might continue being the Doctor for some time or might decide to leave after series six.