What are 3 of the scariest movies you've ever seen?

I don't just want some dumb slasher film, I want films that truly creep out people like me that have a hard time jumping to the scariest of stuff. Some that I've already seen include Suspiria, Paranormal Activity, The Thing, The Ring, The Grudge, Ju-on, Rec, Poltergeist, Silent Hill, Session 9, Scream, Jacobs Ladder, Frailty, The exorcist, Donnie Darko, 28 Days Later.