>>24783937
The one with the cursed Halloween mask I remember scaring me the most in terms of plot. But the cover that scared me the most was from the 2000 series, I think, and it had two rotting zombies on a gravestone. One of their eyes was hanging down by a stalk. Terrified me so much I was afraid of the bookshelf. Don't even remember the actual contents of the book.

Looking back on it, almost every Goosebumps book had amazing art for the covers.