Great post ZenTickling ... I can't answer your question outright, because I don't really think any movies are scary, but I will name my favorite scary movies.
In no particular order ...
1) Misery - Being the King buff that I am, I have always liked this movie. As it is, it was the first King book I read, and the first King adaptation I watched. Kathy Bates as Annie Wilkes is absolutely terrifying. She mixes vicious (hobbling, gross) with an inability to curse (cockadoodie) and any author's worst nightmare ... an insane number one fan.
2) The Shining - This time it has nothing to do with King ... Kubrick/Nicholson make this one. I date you to name someone who could play a more perfect Jack Torrance. Not Stephen Weber, I assure you. One of the first times I saw bewbs was in this one, and then Kubrick turned those tits into gruesome decay and rot. Thanks Stanley.
3) Dawn of the Dead - I am not into the whole "if it came out first it's automatically better" thing. The Beatles may have set the standard, but there are plenty of bands that are better. With that said, I choose Dawn over Night. Maybe it's the amazing technicolor color, or the mall full of zombies. Maybe it's some blockhead getting the upper half of his head lopped off by a helicopter blade. Don't ask me to explain myself, this is a rad movie. Thanks for the great makeup work Tom Savini.
4) The Thing - This remake of The Thing From Another World is a real gem. Any time a movie starts with Norwegian scientists trying to kill a shape shifter assuming the form of a husky, you know it's gonna be a barn burner. Tension and isolation are the key to this film. The scene where they test the blood to find out who The Thing is ... perfectly spoofed in South Park ... is a favorite scene of mine.
5) Scream - Say what you want about this one, it's fucking classic. It's a slasher flick that simultaneously mocks other slasher movies, while still managing to remain hip (by 1996 standards) and scary (by 1996 standards). The background story is believable, the double killer/boyfriend back from the dead twist is brilliant, and the voice/mask combo is eerie as hell. Probably my favorite scary movie
6) High Tension - There are always haters, and this one brought out plenty. Either you'll like the twist or you'll hate it ... if you hate it, watch it again and understand how brilliant the twist is. I promise you it's worth it.
7) Halloween 2 - Yeah, I know, what about Halloween 1. It's absolutely a classic horror film. That's why I don't need to mention it. I love that Halloween 2 is a continuation of the first one. It's later in the night, Laurie is in a spooky hospital, and Michael is about ready to quadruple his kill count. He's ... pure ... e-vil.
8) The Lost Boys - Not really a straightforward horror film, but it's downright awesome. It's got hair-dos, it's got not one but two Coreys, it's got Jack Bauer as a slick and manipulative vampire. What more could one ask for.
9) The Hitcher - I'm just saying Rutger Hauer is really really ridiculously creepy. He puts fingers in french fries, he somehow shoots down helicopters with handguns, he butchers a police barracks without waking Ponyboy Curtis, and he ties Jennifer Jason Leigh between two 18 wheelers and ... well ... she doesn't quite make it to the end, that's for sure
10) 30 Days of Night - I personally thought this was a pretty rad movie. Vampires aren't as cool as zombies, but they are devastating. The premise is perfect in this film ... a town in Alaska where it's night for 30 days ... and there are vampires ... who can only come out in night ...