For me almost anything in Resident Evil games is very well done from a fear standpoint. I recall playing RE1 on the PS1 and when those pixelated dogs jump though the windows in the hallway near the beginning of the game that this really scared me. Later on when a spider that you likely didn't notice is on the ceiling in a room and drops down, my heart dropped down as well.
RE: The true definition of fear in Resident Evil 4 [ENG - ESP]