"Jaws" & "The Exorcist" (the original, not the re-release of 10 years ago). A few moments in "The Omen" (the original) are great because of the great cast. The latter choices are weird because I don't believe in the devil. As for sharks, I believe in them to the point that I'm sometimes sure they might burst through the drain of swimming pools that I'm in.
Honorary mention goes to "When a Stranger Calls" with Carol Kane. ("Have you checked the children?"...."Why haven't you checked the children?"...."The call is coming from inside the house!")
To this day I've seen only the first 20 minutes. The first & only time I watched was the first time I was babysitting as a kid. (Dumb move.) The kids were asleep upstairs, just like in the movie. Right when Carol Kane tries to get out of the house as the shadow descends the stairs, & she fumbles with the locks & rips open the door to see the large man there, the power in the real life house suddenly went out. So there I am, in pitch black in a strange house, a few feet from a stairway. I feel my way over to the corner & sit by the TV, cringing, ready to jump at every move, convinced that a killer is going to come down the stairs but I won't see the shadow because it's dark. Forty-five minutes of this and all of a sudden the power comes on in a flash, with the lights blindingly bright & the TV blasting in my ears. I think there's still a mark on the wall from where I flew into it.
- Jake