Ok, story time.
Back when I was like 9 years old, my family was flying from Texas to London. It was just me, my sister, and my mom. My sister is a few years older than me, and we were siting together watching movies. My sister tells me that I should watch this movie called the Grudge, because it's a really funny movie that I would like. Up until this point, I had never watched a horror movie, and I was a complete scardy cat about all things frightening. So the movie begins, and I notice pretty quickly that this isn't a normal comedy. My sister tells me to just stick through it, as the movie gets better after the intro. Pretty soon, the actual scary stuff starts happening, and in my 9ish years of existence, I had never been so thoroughly fuckin' terrified. I ended up watching like 3/4 of the movie because I couldn't look away. I was straight up not ready to deal with this yet.
This is the only movie that has ever done actual psychological damage to me. For months afterwards, I was scared of the dark, I was afraid of going downstairs in our house at night, I was afraid of being in small rooms by myself, and I actually had nightmares about dead-girl-ghosts stalking and attacking me. That shit still affects me today! When I try to picture a scary ghost in my head, my mind automatically jumps to a smallish pale girl with black hair.