The Exorcist - (William Friedkin;1973;USA) -
A young girl becomes possessed by a demon while a discouraged priest, and an elderly priest familiar with the demon try to save her.
This film is one of the more disturbing horror films I've seen. At the same time beneath the gore and shock value is a two-way look at the film. As Friedkin says, you can see it as evil existing in a horrible world, or how good can triumph over evil. I believe in the latter, although with the addition that not everything can come to a happy ending. There is evil and good, and both win at times, sometimes at the same time. The film didn't make me question my beliefs like some, but it was still a moving film horror film, which is ridiculously rare. Perhaps a little overrated over the years, but a great film.

The Texas Chainsaw Massacre - (Tobe Hooper;1974;USA) -
A group of friends fall victim to a family of cannibals.
Again, one of the few horror films that is actually disturbing. It may be low budget, but it's very effective. Right now I think this is better then Halloween as it proves to be more of a "horror" film. Leatherface has proven to be a memorable character, although he inspired several horrible sequels and an equally horrible remake, which lacked all of the punch this film had. The scenes themselves can be pulsating and the film's final image is haunting, and one of the most memorable in horror.