5 I can think of...
  1. Profondo Rosso (Deep Red). Just the atmosphere of Argento's films scare the crap out of me, never mind the gore. Key scene: The puppet coming out of the closet.
  2. Scream. Although its impact has been lessened by numerous sequels and spoofs and this film itself has it's tongue firmly in it's cheek, it never the less had me hiding behind cushions. Key scene: shock opening.
  3. La Cabina. A short Spanish film about a man who gets stuck in a telephone box. Surely not that scary? Saw it as a 12 year old and would always keep the telephone box door ajar with my foot for years after.
  4. The Flypaper. This Tales of the Unexpected episode was a total one off. Genuinely terrifying and unexpected. Probably would not be shown on the telly today so look it up on You Tube.
  5. Paranormal Activity. Only horror I recall seeing at the cinema and all the better for it. During one particularly nerve jangling tense scene the silence in the room was broken by an audience member, letting out a nervous 'oh, Jesus Christ!'. Summing up how we all felt and not easing the tension.