British actor Matt Smith has been unveiled as the new Doctor Who, making him the youngest person to portray the popular time traveller in the TV series' 45-year history.

The 26-year-old takes over the reins from David Tennant, who announced he will be stepping down from the BBC series after he films four Doctor Who specials in 2009.

Smith will take over Peter Davison's special mantle, who was 29 when he signed to play the fifth Doctor in 1981.

'The challenge for me is to do justice to the show's illustrious past, my predecessors, and most importantly, to those who watch it'—Matt Smith

"I feel proud and honoured to have been given this opportunity to join a team of people that has worked so tirelessly to make the show so thrilling," said Smith on Saturday's BBC One show Doctor Who Confidential.

"David Tennant has made the role his own, brilliantly, with grace, talent and persistent dedication. I hope to learn from the standards set by him.

"The challenge for me is to do justice to the show's illustrious past, my predecessors, and most importantly, to those who watch it. I really cannot wait."

Smith — who studied drama and creative writing at the University of East Anglia — is a relative unknown who first appeared on TV in the 2006 adaptation of Philip Pullman's The Ruby in the Smoke, which starred former Doctor Who companion Billie Piper as Sally Lockhart.

He has also acted opposite Piper in the followup, The Shadow in the North, and in ITV2's Secret Diary of a Call Girl.

He had a leading role in BBC Two's 2007 political drama Party Animals, in which he played a parliamentary researcher.

Had a 'Doctorness' about him

Bookmakers had put black actor Paterson Joseph, 44, as the lead contender and close behind was David Morrissey, who played a man who called himself "Doctor" in the recent Doctor Who Christmas special.

Entertainment writers even guessed wildly that the next one might be a woman, possibly played by Welsh star Catherine Zeta Jones.

Piers Wenger, head of drama at BBC Wales, 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 'Doctorness' about him," he said. "You are either the Doctor or you are not. It's just the beginning of the journey for Matt.

The TV series began in 1963 but was dropped in 1989. There was a 1996 movie before the series returned in 2005 with Christopher Eccleston in the lead role. Tennant took over after the first season.

Smith will be the 11th actor to take on the role.  Filming begins in 2010.