Reposted from January 2007, however, this is for neonite / see her blog about horror films and see if you can help her.

All of these movies have terrified me in one way or another:

1. Frailty (2001)
2. Rosemary's Baby (1968)
3. Ôdishon (1999)
4. The Silence of the Lambs (1991)
5. Blue Velvet (1986)
6. Shaun of the Dead (2004)
7. Peeping Tom (1960)
8. Final Destination (2000)/Final Destination 2 (2003)/Final Destination 3 (2006)
9. Diaboliques, Les (1955)
10. Tesis (1996)
11. Yeux sans visage, Les (1960)
12. Videodrome (1983)
13. Saw (2004)
14. Cri du hibou, Le / (Cry of the Owl) (1987)
15. Lost Highway (1997)
16. The Birds (1963)
17. Dawn of the Dead (2004) (remake)
18. Eraserhead (1977)
19. Locataire, Le / The Tenant (1976)
 20. The Exorcist (1973)

Honorable Mentions:
-Ju-on (2000)
-Ringu (1998)