Tennant became the 10th actor to play Doctor Who in 2005
Doctor Who actor David Tennant has not ruled out the possibility of returning to the hit BBC series after he leaves.
"Who knows what might happen in the future?" he told BBC Breakfast. "The door isn't necessarily closed forever."
The 37-year-old revealed last week he would be relinquishing the role after shooting four more specials in 2009.
But he did admit it was "one of those parts that sticks with you," citing Peter Davison's appearance last year in a Who short made for Children in Need.
The actor refused to be drawn, though, on who might become his eventual successor.
"It's not down to me," said the actor, currently appearing with the Royal Shakespeare Company in Stratford-upon-Avon. "I've got nothing to do with it."
Bookmakers have made James Nesbitt one of the favourites to take over the coveted role.
The Cold Feet star has downplayed the speculation, however, saying he has no interest in becoming the 11th doctor.
Speaking to the BBC's Lizo Mzimba in Marrakesh, Morocco, where he is currently filming new drama Occupation, the actor said it would be "career suicide" for him to follow in Tennant's footsteps.
He did say, though, that Paterson Joseph - another actor who has been linked to the role - "would be great".