Terminator 2, when he took off his skin from his arm, I NOPED out of there. I did finish it the next day though. It's also now in my top ten movies of all time.

Rikki-Tikki-Tavi gave me nightmares as a young child, for years. Still, remembering how much I loved it, downloaded it to show my young kids, gave it a watch while they were out. Hell. No.

Let's just say Orson Wells had no business narrating a children's cartoon.

Return to Oz.

Dooooorrrrrrrtthhyyyyyyyy. GAAAALLLLLLEEEEEEE!

Lots of the answers here make me feel old

Not technically a movie, but the 1990 It mini series has always gotten me. I can watch the newer movies and it won't bother me at all, but that show was masterful in terrifying me as a kid.

Saw Dawn Dawn of the Dead (1978) in the theater when I was 12. Didn't scar me for life, but it did have a big impact.

My dad used to watch horror movies when he was supposed to be watching me, then fall asleep the couch with the movies still going. I don't watch horror movies at all as an adult, I can't handle them, but here's a list of the ones I can remember that I got exposed to while dad was sleeping:

Scanners

Cat's Eye

The Thing

Any old Twighlight Zone episode

The Lost Boys

Gremlins

Whatever show that was with Elvira

There was some show with a talking skeleton at the beginning all the time, I forget what it's called

Needless to say, ANY horror movie scares me, and i avoid them all, even the "funny" ones

Ghost where the demons drag the bad guy to hell. I must have been 6 or 7.

Pet Sematary. The scene with the diseased old lady was the worst.

Braindead/splatter. Guy kills his zombie mother with a lawnmower I think.

Pumpkinhead. Actually kinda sad but still fucked up.

I had an 5 yrs older brother who would force me to watch scary movies.

Aliens. It wasn't the movie itself, it was the TV adverts for it. A two-second shot of a door buckling as something pounded against it from the other side. I was exactly the right age to be shocked by the thought that you can't shut the monsters out with just a closed door.

The original 70s Texas Chainsaw Massacre makes me uncomfortable still as an adult.

The Day After.

Tommy. So much horror for a musical.

There was some movie on TV that I caught a glimpse of when I should’ve been in bed. I was probably about 3 yo. It was some blobby monster which in my memory was a bit like a skinny Michelin Man, emerging from a pond or river. Scared the shit outta me and the memory stuck.

I was like 6 when my grandmom suggested we rent The Amityville Horror. I slept with the lights on for a week.

I don't think it would bother me now if I rewatched it but I've also never wanted to rewatch it.. I guess take that for what's it's worth.

Threads 13 y.o me was not prepared for this, especially as it was set just the next city away from where I used to live.

The Grudge. I saw it when I was maybe 7 or 8? I was at an Aunts house with some older brothers that had it on. Honestly I barely remember actually watching it, but good lord it scarred me until I was at least 18 or so. I could never get the image of hair growing out of random places, turning into something terrifying out of my head whenever I was showering and stuff. I still haven’t rewatched it :D I’m quite a scaredy cat when it comes to horror movies already and I could totally see it giving me nightmares again if it’s anything like I remember as a kid

Duel at Diablo. That guy roasting over the fire...

So when it was a little too young, I slept in the same room with my grandmother during the summer and she would like to watch TV very late at night, even while she slept. Because of that, i would sometimes happen to come across some of the more mature movies that they would be airing. This is a little too specific, but one night they were airing Superhero Movie 2008. I don't remember if I was paying attention or not, but when my grandmother put the channel with this movie on, it was around the funeral scene.

Yeahhhh my young ass was traumatized. Necrophilia is a no no.

I Am Legend

The cure for cancer creating a bunch of rabid, fast moving, sunlight fearing, flesh hungry, "zombies" ... Yeah that was a bit much

I'm old, but "The Mephisto Waltz," a1971 horror film about a dying pianist (and Satanist) taking over a young piano players body. Lots of murder, lots of screaming, and decanters of blue liquid. My parents took me in a drive in to see it, and I guess thought I'd be okay with it at age five, sleeping in the back of the car.

Nope.

Blue liquid still freaks me out.

House of Wax and the Saws.

Was far too young to be looking at stuff like that, and I felt unwell for days afterwards.