The 2017 adaptation of Stephen King's IT helped ensure that a healthy fear of clowns made its way to the next generation, but Pennywise isn't the only form IT takes in the film. IT is a horrifying entity that chooses to appear as the dancing clown most of the time, but IT can be many things. IT chooses its form according to the maximum psychological terror it can inflict.
In Stephen King's book, IT tends to stick to classic horror movie monsters like mummies, werewolves, and Frankenstein's monster. Sometimes, though, IT transforms into something deeply personal to the victim, like a loved one or a bully. Whatever IT appears to you as is chosen because IT knows your deepest fears.
In the 1990s, IT was played by Tim Curry, who set the standard for modern spooky clowns. In 2017, Bill Skarsgård took on the role, and he reprises his version of the ravenous monster in 2019's IT Chapter Two, in theaters September 2.
In the 2017 film, IT appears to the Losers Club in many different forms, each one more haunting to the poor kids of Derry. These are all the different monsters and forms that IT takes in the 2017 film.
It's hard to forget a face as terrifying as the woman in the painting from Stanley's dad's library. Stanley has been afraid of the woman in the painting since he was a child, so IT becomes her and faces Stanley when has to enter the Rabbi's office. By drawing on his childhood fear, IT's transformation is frighteningly effective - so much so that even Stephen King was spooked by her.
IT prefers to haunt as Pennywise the Dancing Clown. Pennywise has been terrorizing the town of Derry for decades, but his favorite prey is frightened children. IT taunts the Losers Club as Pennywise more frequently than any other form. Whether Pennywise is holding red balloons, peeking out of sewers, or hanging out in the background of your favorite kids' show, the dancing clown is easily one of IT's most terrifying forms.
IT comes to Eddie as a festering leper and chases him before eventually letting him go. IT chooses this form specifically for Eddie because of his complicated relationship with illness and his phobia of germs and diseases.
While researching the tragic history of Derry at the local library, including an eruption at an Easter event that took out 88 children, Ben is haunted by the smoldering remains of one of the victims. IT chases Ben through the library and disappears once the Loser bumps into the librarian.