Also, one moment that completely terrified me was in Resident Evil 4 when you enter the tunnels in chapter 4. You just roam around in an empty area with no enemies and the game lets you search hidden items a bit, when suddenly a loud noise happens like a metal grid or something getting smashed open and footsteps start to come at you. And those footsteps are FAST, I tell you, and they get louder and lounder but you see no monsters so you start to think that something invisible runs straight at you. But nothing happens, no monsters, it was all just an illusion. I was scared as hell.
That's chapter 3-2.
On topic: I'll go with something less conventional for the sake of variety in responses, so I say Invisible Enemies mode in REmake. Particularly when you return to the mansion and hunters have spawned. You think there should be one in the corridor around the corner near the save room, but you hear nothing. You think, "Okay, maybe I misremembered," and begin to walk slowly just in case. The next moment Jill's head falls off her neck.
It's in those moments in which you think that you know what to expect that it hits you really hard.