No matter how much you suggest that It is about a group of outsiders finding themselves, overcoming childhood trauma and learning the power of moving on, it's really mostly about fear. It's a story that channels the most innate of our fears - that fear feeds on itself and makes it far more likely that you'll have a reason to be scared when you're already scared. That's not a very elegant way of expressing it, but it's the feeling you get when you're walking upstairs when it's pitch black behind you and you don't WANT to look back. It's the just in case, but it's expressed more overtly.
Because fear is a huge, diverse melting pot of ingredients, the fact that It bases its forms on the fears of its targets means we also get a vast array of monsters and nightmares across the two movies. Some of them are more effective and more affecting than others, but there aren't actually any duds.
Some have big thinking behind them, some are silly, some will follow you up the stairs at night when you least expect, whispering memories of the films at you. And that's why they're great. But which is best?
20. The Librarian
The least of Pennywise's monsters is the most subtle and appears only in the background of the library scene in which the young Ben uncovers some of Derry's haunted past thanks to some newspaper clippings. As he reads and tension builds, we see Ben flipping through pages as they - clearly a projection by It once again - zoom in closer and closer on an image that shows the head of a dead child trapped in a tree after an explosion.
Obviously that's traumatic enough, but the scene's unsettling feel is aided massively by the librarian in the background who freezes and begins to grin ominously. She never gets closer nor appears threatening, she just freezes, maniacally smiling and out of focus to help raise the hairs on the back of your neck.