Actor Sam Rockwell has emerged as something of a muse to Irish playwright and filmmaker Martin McDonagh. Rockwell appeared in McDonagh’s black comedy A Behanding in Spokane when it opened on Broadway in 2010. The actor went on to star in Seven Psychopaths, a 2012 film McDonagh wrote and directed. The pair’s latest collaboration is Three Billboards Outside Ebbing, Missouri, in which Rockwell plays small-town police officer Jason Dixon, a role McDonagh has said he wrote for Rockwell. The film, which also stars Frances McDormand and Woody Harrelson, opens Friday.

Rockwell spoke with Vanity Fair executive West Coast editor Krista Smith about his work with McDonagh, his friendship with actor Chris Messina (The Mindy Project), and his long and varied career, including his upcoming role as George W. Bush in Adam McKay’s biopic of former vice president Dick Cheney.

Vanity Fair: What is it like to work with a writer-director through several projects? How has your relationship evolved, and how as your acting evolved?

Sam Rockwell: [Martin’s] evolved as a filmmaker. He’s a really charming and compassionate person. I think it’s the main thing about great directors, whether it’s Tony Goldwyn or Ridley Scott or John Favreau, any of these guys, Adam McKay—they have compassion. I think a director has to have people skills and he’s got to be compassionate. You hear the horror stories about the directors that aren’t, and they’re antiseptic, and you know, it’s not fun. It’s not fun. I think without compassion, and intelligence, and talent, you’re not going to be a good director.

I think Martin is really flexible now. I think he’s learned a lot, and lets me be loose. When I play a lot of crazy guys, you know, [directors] give you a little leeway. When you play anti-heroes, psychos, you get a little more leeway. Obviously, I’ve learned a lot from doing theater and doing little movies that nobody saw, [about] how to play Dixon. I was ready to play this guy because I’ve done a million drunk scenes on stage and in films that nobody saw.

There’s a little movie that nobody saw called The Winning Season, where I played a basketball coach.

You were fantastic. One of my favorite movies.

You saw The Winning Season?

I saw it at Sundance.

I worked my ass off on that thing!

You’ve done a lot of theater.

The main agenda that Fran [McDormand] and I are pushing is the theater geek [agenda], and Chris Messina would push the same thing. Like, all these people, Woody, Peter Dinklage, John Hawkes, everybody in the movies are theater nerds, you know.

The thing is, nobody in Hollywood cares about theater, but I think it’s important because, by the time Chris Walken gets to that monologue in Pulp Fiction, he’s already done all these great [roles], he’s done Iago [from Othello]. He knows how to chew text. I keep encouraging Messina to get back on the boards!