Sam Rockwell is teaming up with Jon Favreau for DreamWorks' sci-fi western Cowboys and Aliens, according to Heat Vision.

The film is based on a Platinum Studios graphic novel, of cowboys and Indians rising up against aliens.

Sam Rockwell will portray a bar owner named Doc who joins in the pursuit of the aliens. Once Favreau and the writers -- Alex Kurtzman, Roberto Orci and Damon Lindelof -- learned that Rockwell was interested in the movie, they reconceived and expanded the role, which initially called for a heavy-set man.

Cowboys and Aliens begins filming in June.