Based on a true story. The Exorcist.

Since 1973, nothing comes close. My 20 year old daughter was bragging about all of the current "scary" movies that have come out over the past few years. She has seen them all. One night, I asked her to watch the Exorcist with me. (I own the re-released digitally remastered DVD) She looked at the cover and said, "1973, couldn't be that scary." When Regan's head spun around, my daughter stood up and said, "I'm done." I coaxed her into finishing, though she had her hands over her eyes a lot of the time. In the end she told me that no movie she and her friends had ever seen, compared to The Exorcist. I know adults in their 40 and 50's that have never seen it and don't plan to.

Alien (1979).

My favorite is still the original Halloween from the '70's. It's kind of a ritual with me and my wife, I set the DVR and record all the horror movies in October and we watch them all month long. I'm also a big fan of the old black and white Frankentein, Dracula, and Wolf Man movies.

anything with Pee Wee Herman in it is down right spooky to me.

Fright night gets my vote.

I don't watch horror films as a rule, but one I enjoy, when you can find it, is the original House on Haunted Hill with Vincent Price. 

I  forget the name, but it's the one where Kathy Bates gets nekkid.

Terrifying.

the evil dead movies are good campy scary movie

I don't watch horror films as a rule, but one I enjoy, when you can find it, is the original House on Haunted Hill with Vincent Price.

+1 or even the remake in 1999 is a decent movie.

101 Dalmatians scared the crap out of me.  ;D

The Exorcist

http://www.bing.com/videos/watch/video/the-exorcist-in-5-seconds/e6bf11c314733d573ffae6bf11c314733d573ffa-165923980762?q=the%20exorcist&FORM=VIRE6