In Imperium you play an FBI agent undercover with white supremacists. What’s the most disturbing thing you learned?
It’s all fairly disturbing. I was more surprised by the mundane stuff. I imagined that white supremacists would go on internet forums and say horrible things about black people and Jews. I didn’t imagine they’d be swapping poems.
Which conspiracy theories are you a fan of?
I love the idea that aliens might have built the Pyramids or interceded in our progress as a civilisation. I don’t believe that, but I love hearing people talk about it.
What did you think when you read the Swiss Army Man script and realised you’d be playing a flatulent corpse?
That it was, yeah, kinda weird, but mostly what struck me was how funny and inventive it was. There was something really exciting about the levels of imagination at work. I immediately thought: “Holy sh*t, this is going to be something cool.”
The likes of Robert Pattinson, Kristen Stewart and yourself have all used franchise fame to help weird indie films get made. Do you feel a responsibility to
Yeah, but that makes it sound like there’s nothing in it for us. It’s not an act of charity. I think it’s more that we feel a collective release of pressure. We have something that most actors our age don’t have, which is an element of control. We have the option of saying no to things, and that’s such a rarity for most actors. When you have that ability you’d be stupid not to use it.
After JK Rowling lent her support to Owen Smith for Labour leader, some parts of the media re-ran an old story that you’d backed Corbyn. Are you still a Corbyn supporter?
No, not really. I’ve never been a supporter of anyone, it’s just one of those things where you’re being interviewed and you express an opinion and then it becomes ‘This is what he thinks, now and forever’. First of all, I change my mind, and second of all I probably don’t know enough at the moment to say who I support.
In the US, the Republican Governor of Ohio John Kasich recently criticised you for being an atheist, and asked: “What the hell is wrong with him?” So, what the hell is wrong with you?
Yeah, what the hell is wrong with me? I always find it really weird that people who are apparently super-secure in their faith would have a problem with someone not believing. I happen to not believe in God. I completely and utterly support anyone who does believe in God. I don’t think religion is the root of all evil, I think it does a lot for a lot of people. It’s hilarious that at some point that bugged him. He learned that about me somehow and that’s filed away in his brain somewhere. That’s very funny.
Have you seen the play Harry Potter And The Cursed Child?
I have not. I think being there would become very weird and intense for me and then if something’s happening in the audience that would distract from what was going on onstage. I wouldn’t want to be responsible for doing that to another cast.
Now that other people – like the play’s Jamie Parker – are playing Harry, are you essentially the Sean Connery of Potter?
Ha! Yeah, I’ll take that compliment! I’m sure there will be remakes of Harry Potter at some point. They could remake these films tons of times. In 100 years, the Potter series might have had as many incarnations as Sherlock Holmes but I’ll always have been the first. So that’s cool.
You don’t fancy playing older Harry if they make the play into a film then?
No, I don’t. I think it would feel weird, and frankly if they want to make the film now I see no reason why they wouldn’t trust the cast from the play.
Apparently people are often surprised you’re not a dick. What’s the most dick-ish thing you’ve done recently?
They are. My attitude is that it’s nice to have such a low bar. You’re always a pleasant surprise just by being basically decent. I hate actors complaining on set, because we have the nicest and, for the most part, cushiest job. I can’t think of anything I’ve done recently that has been particularly dick-ish, although I’m sure people in my life would disagree.
Imperium is at cinemas now; Swiss Army Man is at cinemas from 30 September