Fans of Harry Potter would be forgiven for feeling that there's something hauntingly familiar about Stephen King's IT. After all, this is a monstrosity who lives to feed on fear, who dials into its victims' most terrifying phobias and uses them against them to its own ends. IT's also a creature whose power is fundamentally tied to perception. In other words, it's only as powerful as you make it in your own heads.
That definitely sounds like something from the Wizarding World, does it not? It should too, because IT is a boggart. Looking at the evidence, there's just no getting around how closely the demon matches the mythology of JK Rowling's most mysterious ghastly creation and everything in IT Chapter Two that deals with how the Losers Club vanquishes it finally (or so it seems), fits even more with that idea.
First, we have to consider the rules of a boggart. In Rowling's own words:
"So the boggart sitting in the darkness within has not yet assumed a form. He does not yet know what will frighten the person on the other side of the door. Nobody knows what a boggart looks like when he is alone, but when I let him out, he will immediately become whatever each of us most fears."
The same is fundamentally true of IT. Beyond an allusion to the Deadlights, the creature's perverse and irresistible draw comes from the fact that it is an unknown. You cannot know its true form, because its form is influenced by who sees it.
And while both Boggarts and IT change their shape according to the biggest fear of the person closest, they CAN appeal to the fears of more than one person, as multiple students at Hogwarts saw Voldemort when confronted with a boggart. In IT, the form of Pennywise is chosen predominantly when IT is targeting a group because the clown is presented as a communal fear. There's more to it than that, though, as we come to explore.
But first, let's start with the simplest similarity...