My personal one was the shining. I ended up watching it over 20 times before I was 12.
I’m spending a lot of time babysitting my nieces (9 & 11). I’m cis male and I would love to hear what women would answer or suggest for me to show them in a cool uncle role.
RoboCop, the Alien movies, Hellraiser. Honestly a lot of the old Jean Claude van Damme movies are fairly hardcore for kids, looking back. Probably a lot of movies because I was allowed to stay up until whenever on weekends from pretty young.
I didn’t realize it until now, but same for me. That scene where the toxic sludge man disintegrated after being hit by a car haunted me. Actually, it was how he was calling for help that did it. I realize this is counter to OP’s question, haha.