The recent Oscar winner, who stars in this week's "Woman Walks Ahead," called IndieWire from the set of his next movie to talk through his many upcoming projects.

Sam Rockwell isn’t slowing down. A few months after winning every award under the sun for his performance in “Three Billboards Outside Ebbing, Missouri,” the actor is back in theaters with another distinctly American film: “Woman Walks Ahead,” which required him to saddle up as a cowboy and learn the Lakota language alongside Jessica Chastain. The recent Oscar winner isn’t stateside for the release of Susanna White’s 1890’s period piece about Sitting Bull and the woman who traveled across the country to paint his portrait, however — he’s in Prague, where production on “Hunt for the Wilderpeople” and “Thor: Ragnarok” director Taika Waiti’s outrageous-sounding “Jojo Rabbit” is underway.

“It is the greatest script I’ve read in so long,” Rockwell said over the phone of the dark comedy that Waititi hopes will “piss off a lot of racists.” Asked about his character, Captain Klenzendorf, the actor divulged a few salient details: “I am a Nazi, a captain in the Nazi army — the instructor for the Hitler Youth,” he said. “I’ve been demoted, and I’m a bit disillusioned. It’s an interesting part.”

A World War II satire about a German boy whose only friend is both imaginary and Hitler (played by Waititi himself), “Jojo Rabbit” also stars Scarlett Johansson, Rebel Wilson, and newcomer Roman Griffin in the title role. It’s one of the more high-profile projects Rockwell has in the pipeline — he’s also playing the George W. Bush to Christian Bale’s Dick Cheney in this year’s “Backseat” — and brought to mind something the recent Oscar winner said during one of his many acceptance speeches earlier this year: that he’d always thought of himself as a character actor. Does he still?

“Allison Janney and I talked about this,” Rockwell said. “I think it’s a very slight kind of diminishing comment when you say someone’s a character actor, because you’re assuming that they’re not able to play Hamlet or whatever.”

He singled out some older models. “In my mind, Jeff Bridges is a character actor and Daniel Day-Lewis is a character actor — they’re also leading men,” Rockwell said. “Jon Voight is another good example. Robert De Niro, Dustin Hoffman, Gene Hackman — all those guys were both. They were character actors and leading men. If you say somebody’s a good character actor, I always think that’s a little diminishing.”

If that’s the definition, it certainly applies to the man who stole scenes in “The Green Mile” and “Galaxy Quest” before leading the way in films like “Moon” and “Choke.” As evidenced by his supporting turn in “Backseat,” however, screen time and billing order don’t change how he approaches his roles.

“That’s a good one,” Rockwell said of the Dick Cheney biopic directed by “The Big Short” helmer Adam McKay. “That’s another great script.” And yet it was also “very daunting, I’ve gotta say. I had a similar experience with this [‘Jojo Rabbit’], in that I have to do a German accent and it’s a very intense part, but it’s also a supporting role. George Bush is a supporting role, too, but it doesn’t feel like a supporting role because you’re putting a lot of work into a small amount of screen time.”

He elaborated by invoking another distinctly American figure: “It’s like if you’re playing Elvis Presley and you’ve only got whatever amount of scenes in the movie, you’re not gonna work any less hard on the part because you’ve got less material. You’re gonna be like, ‘I’m playing Elvis Presley!’”

Rockwell makes good an his reputation as an “actor’s actor” by emphasizing process. “If you’re somebody who cares about acting, you put in a good amount of work and you’re gonna bust your ass. George Bush was no exception,” he said. “Everybody has an opinion about how to play George Bush — and a lot of people have done it very well, like Josh Brolin and Will Ferrell. Everybody’s an expert on this, you know what I mean?”

For practice, Rockwell said he “watched all those imitations, and then I stopped watching them, and I just watched George. I listened to his autobiography over and over and listened to his voice. I taped interviews and listened to those over and over again.” More difficult than perfecting the accent, however, was “trying to get his lips. He talks lip forward, and they did some good prosthetics on me, so I had that going for me. I had that advantage, which Brolin and Ferrell did not have.”

Pulling off a German accent wasn’t the most difficult linguistic feat he’s had to pull off, however. That would be learning Lakota for “Woman Walks Ahead.” “That was like, Jesus Christ, it was really daunting…I had to do a whole scene, a three-page scene, in Lakota, the Cheyenne language. They had a guy named Ben Black Bear, who is one of the leading five Lakota speakers in the world, and he coached me and Chastain and Michael Greyeyes. It was tough.”

Before getting to that point, he had to first land the part — something that didn’t happen until Alexander Skarsgård dropped out and Rockwell was able to get a stronger sense of who he’d be playing. “I talked to [screenwriter] Steven Knight and Susanna, and they were willing to make some changes to the script to kind of incorporate my idea about the character, which was to make him a cowboy,” he says. “He was more of a Dudley Do-Right soldier the way it was written, and I was like — I’d just done ‘Fool for Love’ on Broadway, the Sam Shepard play — and I was like, ‘I don’t really know how to play soldier, so to speak, but I know how to play cowboy.”

Rockwell had explored similar territory before, playing Casey Affleck’s brother in “The Assassination of Jesse James by the Coward Robert Ford” and narrating the 2011 television documentary “Gettysburg.” Even so, playing Colonel Silas Grove presented new challenges.

“Steven Knight agreed to that, and Susanna agreed to that, and I made him kind of like an ex-Indian killer. That was in the script, but I wanted to embrace the kind of ‘Lonesome Dove’ demographic, so to speak. I thought that Tommy Lee Jones, Robert Duvall kind of Old West demographic was missing from the story. I thought we needed to make this guy a more Western character from another time, almost, so that he would be representing that sort of white-man’s-guilt idea. Otherwise he’s just kind of a fix-it guy.”

When asked what awaits him when production on “Jojo Rabbit” wraps, Rockwell sounded excited to announce that he’s “cooking up a little Bob Fosse thing, maybe. We might be doing a little Bob Fosse thing.” Fosse — who won an Academy Award for directing “Cabaret” and earned further acclaim for such classics as “Lenny” and “All That Jazz” — has endeared himself to an entire generation of actors and filmmakers. “I’d be playing Bob,” Rockwell said. “We’re trying to figure out who else would be involved. Tommy Kail [‘Grease Live!’] would direct it.”

Not that getting it made would entirely satisfy him. Rockwell has what he calls “the typical list” of directors he’d like to work with: Paul Thomas Anderson, Steven Spielberg, the Coen Brothers, Wes Anderson, Alejandro González Iñárritu, Denis Villeneuve. After the annus mirabilis Rockwell has had, it’s hard to imagine the feeling isn’t mutual.

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