My #1 scary movie and it is proven to be the most scary for multitudes of other people is THE EXORCIST.
I, as a grown man, had nightmares after this movie. Many people needed to see psychiatrist after the viewing of this movie to help them deal with its aftereffects.
As to other movies...... I saw THE INCREDIBLE SHRINKING MAN as a young child and it affected me for quite some time(this was before ratings). It certainly stopped me from running through the clouds of DDT they used to spray in the neighborhoods back then( for those that haven't seen the movie, a cloud of something made the guy shrink).
Of course, all THE NIGHTMARE ON ELM STREET movies.
Well, it's late, time to go to sleep......
WAIT!!!!!!!..........
I can't go to sleep!!!!!......
What a dilemma!!!!!
I guess I'll stay up and watch a cute little girl spit green pea soup at a priest.
Nighty Night.