Cradle - Thief 3 - consistently creepiest level. The tensest levels I've played are Alien vs Predator 2 as a marine with difficulty at max but they weren't as creepy as the Cradle levels.
Best bits of Silent Hill games - i.e. the really creepy, deeply odd stuff: like what in the world is Pyramid Head doing to that thing? I really hope its not what it looks like...
Single creepiest moment - tie between the bit in Fear where spooky little girl appears outside window of room you're in, then persists in fading from view like she normally does so you have to step out and see what's going to happen... and sneaking around in System Shock 2 with the midwives chattering to themselves in the dark about 'the children'...
Creepiest creature - the poor zombie in Half Life 2 covered in black poisonous headcrabs. He seems in such pain and misery under their weight, and then he starts tossing them towards you...
Try to be reasonable... its easier than you think...
