Pennywise isn’t really an evil clown. Though we know him best as one of the most famous evil clowns in pop culture, Pennywise isn’t actually a clown at all. No, that’s just the form that the evil shapeshifting entity that haunts Derry, Maine, preying on innocent children in particular. The entity is just that, an ‘It’,...What is Pennywise the Clown?
Pennywise is the clown form of "It," an eternal, shapeshifting being that feeds off fear, specifically fear of children. It's unclear how, exactly, Pennywise got his name.