Most Helpful Girl
I'm sure there are better options than these, but they're the first two that I thought of
1. Rosemary's Baby. All the build up and anticipation, and then you get that chilling ending. Just wonderfully done.
2. Strangers on a Train. I mean you have Alfred Hitchcock, master of suspense, how could you go wrong? The last 15 minutes made me realize what "on the edge of your seat" really means when watching movies. I was practically hyperventilating, it was so perfect.1