For weeks Jon Favreau and Sam Rockwell have both been neck-deep in the Iron Man 2 publicity circuit, but apparently they're not quite sick of each other. THR reports that Rockwell has signed on for a role in Favreau's next film, Cowboys and Aliens, which starts filming this summer in New Mexico.

Rockwell will be playing Doc, a bar owner who helps the humans fight off the alien horde that arrives in the Old West. He joins Daniel Craig, Harrison Ford and Olivia Wilde in the film, and the part seems to have "comic relief" written all over it. Screenwriters Alex Kurtzman and Roberto Orci apparently retooled the part specifically for Rockwell when they learned he was involved, so I guess we should expect the blockbuster comic relief with a dark Rockwell twist. It's a little odd that the guy formerly known for indies is taking an extended spin in blockbusters, but really, the more Rockwell the better-- particularly if it's Rockwell in a cowboy hat.