(Spoilers for IT, whether the miniseries or the movies, take your pick. Although I've never watched the Miniseries. I might one day though)

Anyways, for me, I'd say Stanley Uris' death and the ending narration (or whatever you'd like to call it, I don't really know) in It Chapter Two.

Eddie Kaspbrak's death is sad too, but after so many rewatches of the movie it really doesn't hit nearly as hard as Stan's still does.