Peter Jackson's little-seen movie had an absolute killer poster, with a brilliant tagline to boot; 'Dead Yet?' Though this film is not considered one of the best horror movies of the decade, the poster certainly should be. It is a masterstroke in how effective a minimalist approach can be.
It is also genuinely nightmare-inducing; slightly ironic for a film that leans more to comedy that out-right horror. If there is one compliant, it is just that, that with horrifying artwork like this, The Frighteners film didn't do the poster justice.
Honourable Mentions: Scream, Candyman, Army of Darkness