Page last updated at 12:27 GMT, Friday, 30 October 2009
David Tennant has admitted it's hard giving up what he calls "the best job in the world" as Doctor Who.
David Tennant
His last series of adventures start on TV in a couple of weeks with The Waters of Mars and then two Christmas episodes which see his final exit.
He says it's going to be difficult to hand over the reins to new Time Lord Matt Smith.
He said: "I'm really excited for him but I remember how exciting it was starting out on this kind of a journey - and nerve-wracking and a bit overwhelming but just such a kick.
"So I'm jealous he's going through that now but brilliant and it couldn't happen to a nicer chap."
'More epic'According to David, the final Doctor Who episodes, which he filmed back in April, are very sad in places.
Continue reading the main storyDavid Tennantit's a bit like being President of the United States, I think you always get to be called the Doctor.
He added: "Because you can only tell the story of a character dying once it allows you to go to places you haven't quite been before.
"It allows you to tell types of stories that you can't do when it's an ongoing series.
"It allows it to be bigger and more epic, and sadder and wilder, and the stakes are just that bit higher."
What happens nextDavid's a massive Doctor Who fan, so not being a part of the cast will have its advantages.
"I'm sure it'll be a bit odd at first to watch somebody else playing the part but I'm really looking forward to not knowing what happens next as well," he said.
Matt Smith Matt Smith will play the 11th Time Lord after David Tennant's exit
"I'm looking forward to being a viewer again because I've always loved Doctor Who so I can't wait to sit down and watch a new one."
However, it won't be easy to walk away from such a huge role without being eternally linked to it, something which David doesn't mind at all.
He said: "I do think it's a bit like being President of the United States, I think you always get to be called the Doctor.
"I will always expect, when I see you in the future, to refer to me as the Doctor, clearly."
His replacement, 27-year-old Matt Smith, is the youngest actor ever to take on the role of the Time Lord.
Little-known actress Karen Gillan has been unveiled as the next assistant.
In terms of David's future plans, he's already filmed a BBC version of Hamlet, which will be on TV over Christmas.
He's also landed roles in World War II drama Glorious 39 and the second St Trinians movie: The Legend of Fritton's Gold.
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