The actor, 27, has gone down a storm in the horror movie – and was kept away from his young co-stars as much as possible.
“The first time we saw him altogether was the projector scene,” Wyatt Oleff said.
“It got our real reactions,” Jeremy Ray Taylor added.
Finn Wolfhard, who plays Richie, added: “I was so freaked out.”
“It was terrifying,” Wyatt laughed.

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Producer Barbara Muschietti said: “We wanted to keep [Skarsgard] away because we wanted the reaction to be real.”
“It was authentic to how kids should be reacting,” reasoned Seth Grahame-Smith, another producer.
The child stars have spoken often about how scary Skarsgard was.
Jack Dylan Grazer plays Eddie, and said: “When he’s up close in your face, screaming at you… it’s insane.”
And Sophia Lillis, who plays Beverly, likened him to a “demonic animal”.
Indeed, the movie has been terrorising audiences worldwide for two weeks now.
It’s already become the highest-grossing horror movie of all time, and a sequel is en route.
It is out now.