The Exorcist-couldn't sleep good for months. Still sleep with a small night light on because of that movie.
Have attempted to watch it many times (trying to desentize myself) but still have never been able to watch the whole movie in one sitting. I cover my eyes and ears so much I've never seen the whole thing. Guess it was and is so scary to me because the movie was based on a true story. The book came out in the 70's and I read it when it came out but the book didn't scare me. Could not visualize what I saw in the movie. The movie put into pictures what my mind could not comprehend and "see" when I read the book. Does that make sense to you?
Alien, The Thing (both versions), and Aliens were terrific movies. Although not a horror movie, The Creature From The Black Lagoon was a very good monster movie in it's day. Incredibly good special effects for it's day. The creature was very real looking.