It movie: Pennywise actor reveals the true story behind TERRIFYING performance

The film, based on the iconic Stephen King novel of the same name, was released last Friday and has already raked in a huge amount at the box office.

The movie managed a hefty $117 million in the US - way up on its initial estimates of $50-60 million.

Skarsgard, who plays Pennywise, has been particularly praised for his performance.

On the clown’s menacing attack, he told Rolling Stone: "I don't know if you've seen kids run like this, but they move their arms way too fast, and it looks really, really funny.

​“And I just loved the way my brother ran as a kid. It was just out of sync. 

“So I incorporated that into the character, and you get this really explosive effect. 

“It's really unsettling when it happens."

It is thought that a sequel - It: Chapter Two - is officially in the works.