Nightmare Fuel / Jak and Daxter: The Precursor Legacy

• The Lurker Shark. Mostly because of the build-up with the heart beating. If you ignore the warning it eats Jak whole.
• Some of the Lurkers have rather scary appearances.
• The Dark Eco Plant boss in the Forbidden Jungle looks kinda cartoony, but it's still pretty creepy in context. Worse though, is the alternate death animation if it kills Jak with its bite; the thing pulls Jak into the air, snaps its jaws close on him with a Sickening "Crunch!", and then swallows him. And while it's not quite clear in Jak's case, Daxter can be clearly seen trying to jump clear at the last second before falling into it's mouth, meaning he was presumably digested alive.
• Spider Cave is pretty creepy...for obvious reasons.
• The Precursor Robot final boss also has a rather intimidating appearance as well, especially with all those extra enhancements done to it.