Watch: David Harbour Turn Into a Total Monster for 'Hellboy'

David Harbour, who you probably know best for playing supporting characters, is already a towering figure if you see him walking down the street. But for his latest role as the titular character in the Hellboy reboot, he shows his true potential as an actual monster.

"I started off the process thinking that I wanted to get really cut and shredded,” Harbour says. “But during the fittings and make-up tests I realized that that was not what this character is about. This character is a massive force that needs to move more like a wrestler-turned-MMA-brawler than a ninja. He doesn’t want to even be in the fight, but once he steps in, it ends quickly. He needed to be completely monstrous.”

In order to accomplish the transformation from everyman sheriff in Netflix’s Stranger Things to demon superhero, the actor was connected with Drive495 owner Don Saladino, who previously bulked up the bodies of Ryan Reynolds and Sebastian Stan.

“I was blown away by David’s dedication to the process,” Saladino says. “Especially given the fact that he wasn’t training regularly before we started to work together.”

Over the course of 10 weeks, the two met at Saladino’s gym for intense sessions that included weightlifting, sleds, and kettlebells, in addition to mobility work. “By the end he was moving around the room like a Mack Truck and deadlifting 400 pounds with awesome form,” Saladino says.

“I can feel the power and the muscle that I built up through working with Don as hard as we did,” Harbour says. “And it feels good.”