Hey Shayla: Although many before me have named some really good ones, allow me to interject a few of my own, as well as some listed.
The Exorcist: It took me 3 times to watch that to the end, 8, 10, and finally at 14.
Salem's Lot: A Real Vampire Flick
Carrie is a good one
Stephen King's IT: A clown that will make you not like clowns any longer.
I like the second Friday The 13th...It had more surprises.
Near Dark and The Lost Boys are two additional good Vamp flicks.
The Thing is pretty good too.
The original Texas Chainsaw Massacre, but the remake is descent.
The Hitcher with C.Thomas Howell is good...waaaaaaaayyyyy better than the remake.
The Evil Dead...That will have you thinking
I have more, but I hope this helps.