The mannequin parts of Condemned. They don't jump out at you, they just appear in neat rows behind and in front of you after a flash of light and they stare with their lifeless faces.
Also the bear chase sequence in Condemned 2 had me shitting myself and the bit in the magic theater when the lights go out and there are big rings of fire spinning about around you and flashing on and off and black gooey things are appearing out of the ground trying to kill you.
Also in Condemned 2, being chased by the big metal thing on the boat level was scary. And one of the last levels where you're going through corridors and there are skinless people all tied up and hanging upside don from the ceiling making ear piercingly terrifying screams.
Or the bit near the start of Condemned 2 when you folly Vanhorn and see black tar coming out of his eyes and you go through a room covered in tar r goo or whatever and little black gooey people jump out of giant sacks from the ceiling.
Almost forgot the doll factory where the little babies crawl up to you and explode. I know they're dolls but they look so much like actual babies it just creeps me out.
Almost forgot about the scene in the bowling alley level when you see all the torture devices. It didn't so much scare me but it un nerved em and disturbed me. I think I've actually repressed that memory since I had to be reminded about it yet I could remember all those others off the top of my head.
<3 Condemned.