To this day, I don't think I have watched the Exorcist all the way through. It still scares me to this day (and I am fifty). Stephen King's IT is pretty scarey too. Fallen is another scarey one. And the Shining. Make me stop please
It truly is hard to beat the Excorcist..The updated version is scarier to me than the older version though. It truly fits in the Horror and Scary category. I've always thought the greatest spoof film ever would be if someone merged it with Mommy Dearest...think about that one for a minute..lol.
Some others for your consideration..hopefully fitting both Horror and Scary.
The Omen..original
The Thing..
Halloween 78
Hellraiser.
Children of the Corn..I actually had to stop on the side of the road to pee when i watched this originally...right next to a cornfield..gave me the heebee geeebees.
Jeepers Creepers.
The Fly.
My best Horror movie, Till Now is Paranormal activity and from the recent Releases, i would like to go with the Mothers day and Scream 4, These movies are just awesome movies to watch.