Everything That It (The Monster) Turns Into In 2017's 'It'

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 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. 

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 lurking in the background of your favorite kids' show, the dancing clown is easily one of It's most terrifying forms. 

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 those who perished. It chases Ben through the library and disappears once the Loser bumps into the librarian.

According to the book, the Deadlights are actually It's true form. We briefly see them in the gullet of Pennywise when It uses them to transfix and hypnotize Beverly. The Deadlights exist in a higher plane of existence and appear in many of Stephen King's works. 

While It is the real monster of the movie, Henry Bowers is a close second. He terrorizes the Losers Club whenever he can, and it is revealed later in the film that he is more than just a troubled kid - he's an actual sociopath with barbaric tendencies. It convinces Bowers to end his own father when It appears to the unstable teen as the host of a kids' television show.