Sam Rockwell saddles up for "Cowboys and Aliens"

Actor Sam Rockwell poses for a portrait while promoting the film ''Moon'' during the Sundance Film Festival in Park City, Utah, January 17, 2009.

LOS ANGELES (Hollywood Reporter) - Sam Rockwell is reteaming with Jon Favreau for another comic-book adaptation, DreamWorks' "Cowboys and Aliens."

Rockwell, who portrays arms manufacturer Justin Hammer in the Favreau-directed "Iron Man 2," has joined the cast of "Cowboys," the alien invasion-meets-the Wild West project that Favreau begins shooting in June.

Daniel Craig, Olivia Wilde and Harrison Ford are already cast in the tale, based on a Platinum Studios graphic novel, of cowboys and Indians rising up against aliens.

Rockwell will play 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" keeps Rockwell, who is known more for indie fare such as "Moon," working in the big-studio world, at least for another movie.

Steven Spielberg, Ron Howard and Brian Grazer are producing along with Scott Mitchell Rosenberg.