It Movie Pennywise
Bill Skarsgard as Pennywise.Warner Bros

Since its terrifying debut trailer, upcoming horror adaptation It has looked like it'll be one of the big hits of the year. Based on the book by Stephen King, the film will tell the story of a seemingly-cursed US town and sightings of a creepy clown that's haunted it.

Pennywise the clown is being played by Swedish actor Bill Skarsgard, but over the weekend it emerged that Oscar-winner Tilda Swinton was once a front-runner for the horrifying role, first made famous by Tim Curry in the 90s TV mini-series.

The news was revealed by producer Barbara Muschietti during a set visit (via Vanity Fair) after a reporter asked if Swinton had been considered. Surprisingly, she said yes.

"She wasn't available," said Muschietti, whose brother Andrés directs the film. "No, no I swear to god. She was not. We had a slot to shoot the movie and she wasn't available so she didn't even audition. But of course, we all thought about it."

"We auditioned literally hundreds of potential Bob Grays or Pennywises and it was an amazing process," she said. "We got to audition people that don't audition anymore and a huge gamut of talent; women, younger age, older age, we really went through the spectrum of actors."

Originally, British actor Will Poulter was set to take on the role, but a scheduling conflict put that to rest so Skarsgard was called up.

Muschietti went on to discuss what Skarsgard brought to the role, claiming it to be closer to the source material than Tim Curry's portrayal.

"For us, the Pennywise is the Pennywise in the book which is quite different," she said. "I think Bill went for that, and he did an amazing, amazing performance and we gave him several tests. Again, because he's a shapeshifter, we wanted to make sure that he could play in different grades, right? And he did.

"He's amazing. And what's even more amazing is that he kept the character very unpredictable, and that's what scares us the most, when you don't know what way he's going to go."

It is set in the 80s on film, rather than the 50s, and concerns a group of children who encounter Pennywise the clown, a seemingly supernatural creature living in their town's sewers who may be responsible for a string of tragedies in the area.

It is set to release on 8 September.