Board Thread:Questions and Answers/@comment-29414935-20171110124647/@comment-3364901-20171110182033

probably better described as a "fragmented" being - there is only one true "IT" but the entity can have many different avatars, Pennywise (in all his forms) is only one such avatar.. when the Losers finally kill him they only kill a part of "IT", there's still more of the entity out there.. it's just assumed that by killing Pennywise they've limited "IT" a little in terms of how it interacts with the town.