LONDON – Britain’s best-known time traveler is ending his journey.

The BBC has announced that Scottish actor David Tennant will leave long-running science fiction series “Doctor Who” in just over a year.

Tennant has played the show’s time- and space-traveling alien hero since 2005. He will appear in a Christmas special and four hour-long episodes to be aired in 2009 and early 2010. But he said Wednesday that when the series returns for a full season in 2010, “it won’t be with me.”

“This show has been so special to me,” Tennant said. “I don’t want to outstay my welcome.”

“Doctor Who” was first broadcast in 1963 and is one of the BBC’s longest-running and most popular programs. Tennant is the 10th actor to play the title character, who has the power to regenerate in a new body.

Classically trained Tennant, 37, is currently starring in Shakespeare’s “Hamlet” for the Royal Shakespeare Company.