THE NEW YORK TIMES – Bill Skarsgard was calling from his native Sweden, where “It” — the much-anticipated horror film in which he co-stars — was set for a premiere in Stockholm on Friday. “It’s more of a family gathering,” Mr. Skarsgard said. “I’ve invited all my cousins and uncles, and my sister, who works in event planning, is throwing the after-party. My brother Alexander did the same thing with ‘The Legend of Tarzan’ last year, so he inspired me.”
But Pennywise, the child-killing clown Mr. Skarsgard plays in this adaptation of the 1986 Stephen King novel, is a far cry from Tarzan. “It will be fun to see my entire family jump while watching my performance,” Mr. Skarsgard, 27, said.
His relatives probably won’t be the only ones startled by his disturbing turn. “It” is expected to devour the competition at the box office this weekend, building off the repeated reports of creepy-clown sightings around the United States and in Britain in recent years. “These are grown men who put on makeup and try to entertain children,” Mr. Skarsgard said of professional clowns. “If you ask anybody what they think of clowns, it’s associated as much or more with something crazy and scary as it is something joyful. I don’t think this film is going to help that.”
“It” will no doubt be a boost to the career of Mr. Skarsgard, who was previously seen in the sci-fi film “Allegiant” and Netflix’s supernatural drama “Hemlock Grove.” He’s fine with the fact that in this film he disappears underneath layers of prosthetics. “I’m a pretty private person, so I don’t mind not being recognized,” he said. “It’s nice to hide behind the makeup.”
The process of transforming into Pennywise took two and a half hours, but that wasn’t the most grueling aspect of embodying the character. “Normally when you do a movie, you have those mundane days when it’s like, ‘Today is the scene where I get coffee,’” he said. “With this character, there were none of those. Everything I did took 100 percent of my energy. It was by far the most exhausting character I’ve ever done, physically and mentally.”
Like the shark in “Jaws,” Pennywise doesn’t get much screen time in “It,” making his sudden appearances all the more shocking. Mr. Skarsgard didn’t begin to work on the film until a month and a half into production, long after the actors playing the high school outcasts who unite against the psycho clown had started. The director, Andy Muschietti, suggested Mr. Skarsgard stay away from his young co-stars before he shot his first scene in character.
“Pennywise was this looming force they knew was coming but hadn’t seen yet,” Mr. Skarsgard said. “That built an excitement in the kids you could feel when they saw him for the first time. They were probably a bit scared.”
Mr. Skarsgard felt fear himself when he landed the role after a long audition period that included “a callback, a screen test and sending additional self-tape from Stockholm before it was official,” he said. “I was equally as excited as I was terrified when I booked the job, because now these people expected me to pull it off. It was a nervous time.”
After extensive preparation that involved makeup and costume tests and consultations with a clowning coach, Mr. Skarsgard came up with a conception of the character in line with Mr. Muschietti’s vision. “Pennywise is constantly on the level of bursting,” the actor said. “His voice is this shaky, crackly thing. At almost any moment, he could lunge at you.”
The villain is so far removed from the soft-spoken Mr. Skarsgard’s own personality that he’s not concerned about getting typecast. “I wouldn’t want to be associated with one character, because I want to be able to do different roles,” he said. “Pennywise looks and sounds so different from me that I could do a rom-com next, and people probably wouldn’t even know I was the same guy.” (In fact, his next role is in another Stephen King-inspired project, the Hulu drama series “Castle Rock.”)
No matter what lies ahead in his career, Mr. Skarsgard can count on the support of his family, including his older brother Alexander and father, Stellan, also a renowned actor (“Good Will Hunting,” “Breaking the Waves”). “They were always encouraging, but I’ve tried not to seek advice from them, because I wanted to feel independent,” Mr. Skarsgard said. “As I grow older and more comfortable with who I am, I realize asking for help is important.”
He said Alexander saw “It” at its recent Los Angeles premiere and praised his work.
“I’m proud of the film, and it means a lot when I get to show it to my family and they appreciate it,” Bill Skarsgard said. “It’s a great feeling.”
A version of this article appears in print on September 9, 2017, on Page C1 of the New York edition with the headline: Playing a Clown Can Be Scary Business.