The Swedish actor, 27, has shot to superstardom in Andy Muschietti’s horror, based on Stephen King’s novel.
Pennywise, the iconic villainous clown, has been spooking audiences worldwide – and Skarsgard has said that his voice started with a disturbing laugh.
“The voice for me sort of started out with a laugh,” he told Variety’s Playback podcast.
“I was playing around with a laugh. I wanted the laugh to not be a laugh, a laugh to be something that’s on the verge of a panic attack and crying at the same time.”
He continued: “When I started doing it just by myself, I started to creep myself out.
“It doesn’t sound like a real laugh which goes into the aspect of the character not being human or a perfect clown.”
Skarsgard is due to reprise his role in the sequel to It, due in 2019.
His scary performance has been the subject of a hilarious series of online parodies – courtesy of the Twitter account @Pennywise_Dance.
He is seen in a string of video clips, dancing hilariously to various pop hits. Watch a few here.
The film itself has recently become the highest-grossing horror of all time.
It is out now.