He's known for battling Daleks but David Tennant could soon be taking on dragons and ring wraiths if the latest rumours are to be believed.
Some people think he might be lined up to play the hobbit Bilbo Baggins in the latest Lord of the Rings film.
The Dr Who actor is rumored to have pulled out of filming his latest project Burke and Hare.
And some people are speculating this might be because he is going to be working on The Hobbit.
His Burke and Hare co-star Simon Pegg apparently announced on his Twitter page that David Tennant had left the film, but didn't say why. The announcement was later taken down.
In the Lord of the Rings films the hobbit Bilbo Baggins was played by Sir Ian Holm.
But in the latest film Bilbo is much younger, so some people think a different actor will be playing him.
Tennant hasn't said anything about playing the hobbit.