A major reason Bill Skarsgård took on his first big action movie is because he loves MMA and UFC, says Boy Kills World director

While he may have played the Marquis in John Wick 4, Bill Skarsgård didn’t get to partake in much action in that hit franchise. In fact, the actor is probably better known for his horror performances, thanks to his terrifying portrayal of Pennywise in It, as well as roles in Barbarian and Hemlock Grove.

This all means that when it came to casting his action thriller Boy Kills World, director Moritz Mohr tells GamesRadar+ and the Inside Total Film podcast that Skarsgård wasn’t his first thought. 

"I saw him obviously in the It movies and a couple more movies and I was like, 'Yeah, fantastic actor,' but I would be lying if I told you I was pointing at him going like, 'Yeah, he needs to be the next action guy,'" Mohr says. "I didn't even know he was interested in that and we were looking at one point at action guys. Who can do a lot of the action themselves? So we don't have to double everything and it was coming from a very practical side and somebody suggested Bill, I was like, 'Well, would he do it?'"

After he was mooted for the lead role, Mohr said he started plotting out how it could work to cast him as Boy. The lead character is a deaf and mute man on a mission of revenge to kill those who destroyed his family. Trained by an elite warrior (played by The Raid star Yayan Ruhian), he’s a weapon of destruction, which he proves in some seriously brutal action sequences. 

"He's amazing," adds the director. "He's super expressive with his face, that alone is one big selling point for Boy and he’s a very physical actor but no action movies come to mind. [On] that first call with him, he was amazing and I was like, 'So yeah, we got the acting part covered, of course, you would knock it out of the park and I know that, but are you up for doing action?' and he's like, 'Absolutely. Big MMA, UFC fan. I want to get in shape. I want to train. I want to do this the right way.' I was like, 'Okay, if you say, so I'm inclined to trust you there.'"

Mohr goes on to say that he was so impressed with the actor’s transformation for the final movie. "We sent somebody over to Stockholm to train with him, the basics, and he really committed to that part," he adds. "When I saw him on the first day of shooting without a shirt, that was something, he really delivered on his promise."

Alongside Skarsgård as Boy, the movie also stars Jessica Rothe as June 27, Michelle Dockery as Melanie van der Koy, and Stranger Things actor Brett Gelman as Gideon van der Koy, members of a brutal family ruling the dystopian locale. Hilariously too, Bob’s Burgers star H. Jon Benjamin voices Boy’s inner voice, a delightful disconnect from Skarsgård's action hero. 

Elsewhere in our conversation with Mohr, he shared some insight into the R-rating and working with producer Sam Raimi. For our full chat listen to the Inside Total Film podcast, out later this week. 

Boy Kills World is in US theaters and UK cinemas on April 26. You can also check out our guides to all the other upcoming movies on the way in 2024 and beyond as well as the best action movies of all time.