Cannibal Holocaust.
The Thing (the 1980s version).
Those were the two flat out horror movies that got me out of my seat. The first one, my buddy and I departed the cinema post-haste.
The second one, I lasted until the end.
That’s for the horror movies. For suspense, which I would call a subgenre of horror, only one stands out:
The Door (a Japanese suspense drama).
I generally avoid horror movies and HATE jump scares.
That having been said: ALIEN scared the living shit out of me. Saw it in a theater when it was new (1979). I was cringing, literally looking between my fingers and even looking away from the screen, like a ten year old at an old fashioned “monster movie.” Except this time I was 30.
30 Days of Night: As Barrow, Alaska descends into winter darkness for 30 days, a ship of vampires comes out to feast. A great take on the genre. N.B.: under no circumstances watch the sequel.
The Descent: A group of women decide to go caving and find much more than they bargained for.
Both of these movies had me turning on all the lights in the house.
Ah yes, The Descent, seconded. The bit where they crawl through the very narrow tunnel is so incredibly claustrophobic
And then the the gut punch at the end when you realise she is hallucinating finding a way out
The original Predator scared the crap out of me, especially the beginning when they had no idea what it was. Something just burst of the jungle, ripped an uber-macho heavily armed commando to shreds and vanished….until the next time. They had no idea what it was or where it was coming from and it was terrifying.
The series became rather comic-booky later on but the first half of that first movie - Oh.My.God.
This. I watched this by myself on a Blockbuster rental VHS tape years ago because my wife didn’t like horror movies and my son was too young. One of the plot points is a mysterious phone call the doomed people received announcing their forthcoming death in 7 days after watching a cursed VHS tape.
At the conclusion of the film, at 1 or 2 o’clock in the morning, my house phone abruptly rang. 
I thought I was going to have a heart attack. I didn’t pick up.
As a parent, here are the three scariest horror movies, with the caveat that the first one isn’t necessarily a horror movie but is still really fucking scary:
Pan’s Labyrinth
The Orphanage
The Babadook
The first one I knew nothing about, going into it, except that Guillermo del Toro is a genius. Holy goddamn shit. My wife and I went to the bar afterward, ordered shots of bourbon, and sat in stunned silence.
The Orphanage is the one that made my wife say, “I’m no longer watching horror movies with children. Parenthood has changed me.”
So I watched The Babadook one weekend when she left town. It’s the only movie that’s scared me so much that I had to turn it off. I stomped around the house cursing loudly, then ate some dinner, then cussed a bunch more, before I could turn it back on and finish it.
That said, I don’t know that any of these movies hit non-parents in the way that they hit me. They’re all excellent, but the terror in them hits me in the parenting heart.
And as a caveat, The Lost Boys is WAYYY cheesier than I remembered. My 16yo daughter is a real horror buff, and we watched it recently, and hoo boy.
Hehehe, the day after we saw the movie my future wife and a friend were studying in her friend’s house, it was about 2 PM and the neighborhood was absolutely quiet.
Then the phone ringed and both of them jumped about a meter in the air.
Everything in The Conjuring franchise.
Yeah, that’s the problem with Alien – you really need to see it on a big screen. When I saw it in the theater, it was one of those cinemas that showed 70mm prints on a huge curved screen. We got there late and the only seats we could find were front row, looking straight up. I had to keep moving my head back and forth to see the whole screen. And I just about crapped my pants when the facehugger jumped out of the egg.
yeah that’s on my list (we have a projector and a white stucco house, we’re gonna watch it on the side of the house)
The Shining, The Thing (original), and Predator (original) are must-sees. Especially The Thing, which is my all-time favorite horror film.
Another favorite of mine, which doesn’t often show up in “best horror” lists for some reason, is The Strangers. It mostly takes place inside a small house, and most scenes are quiet, foreboding, very suspenseful. The pacing and direction is just done so well. When I was watching it I said to myself, “Finally, a writer & director who knows how to make a film truly suspenseful!”
Mama(2013), because nothing is creepier than children acting creepy.
Okay, I’ve been doing some looking of my own, and here is my list of favorite horror movies:
These are not listed in order of favorites, but my personal recommendations are sinners, alien, scream, and the exorcist, if you guys also want some stuff to watch.
The movie’s title (unlike the book) is just The Haunting. Make sure to watch the 1963 version, not the remake.
The Ring
Oddity
Bring Out the Fear
Session 9
It Follows
Burnt Offerings
Another vote for the The Shining, and surprise at being the first to name The Silence of the Lambs (which has no supernatural elements (I don’t believe in anything supernatural)).
While The Shining relies heavily on the supernatural, it’s a rare instance where the line between supernatural and insanity is blurred so well, I can suspend my disbelief.
The Silence of the Lambs is probably my all time favorite movie, but I wouldn’t call it particularly scary.
I thought about including that one. I really liked it, though I didn’t find it all that scary. My husband on the other hand, was deeply upset by it. I thought that was interesting because I’m the one with an actual history of child abuse.
Pan’s Labyrinth is terrifying. I had to leave the theater twice during the realistic parts.
If you want to make it even creepier, watch the infamous pale man scene set to Tool music.
I don’t find it scary anymore, since it’s been so well-known (and mocked) for so long (similar to The Shining).
But when it first came out, I was around thirty, and it was the first movie that I found scary since I was a child.