there's three that come to mind, one is in Ys 2 where there's a demonic severed head that vomits out some worm like monster and maggots that you have to fight
the second is this giant rotting corpse in Castlevania Symphony of the Night that you have the break apart limb from limb w/ big flys...
Whether it's horror games or just chilling segments in games, you're bound to have run into something really nasty looking. Whether it's visually or conceptually, what are some of the most unsettling enemy/boss designs you've seen in a game?