It Chapter 1 & 2: Every Monster Explained & Ranked
1. Pennywise
He's not in the second Chapter enough, but Pennywise will always be the best thing about It's scary armoury of monsters, not least because of Bill Skarsgard's performance.
He is part kids TV presenter part full-blown psychotic monster and the fact that he can send shivers up your spine just by making his eye go a bit wrong is genius. He obviously dials into the essential fear of clowns (based partly on the idea of kids not being able to trust anyone in masks) and it's very much true to him that a horror presenting itself as something friendly and welcoming is even worse.
That is, after all, how he entices his youngest victims into his grasp.
Pennywise has to go down as one of the greatest horror creations of all time and Skarsgard's performance on the big screen across both movies confirms him as one of the best horror performers ever too. It's almost enough to want to see him in the third movie that's currently being whispered about.