What is the greatest horror opening of all time? (Spoilers)

[Zillamon51]

Both versions of Dawn of the Dead have great opening sequences. The original tells the audience exactly what the threat is, and the chaos in the TV station is a microcosm of the larger world. The remake's opening, up to and including the credits, is some of the best zombie stuff ever put on film. Both set up their worlds perfectly.

I've gone through and liked a lot of posts here with selections I agree with. So many great horror opening scenes / sequences. Impossible to choose just one.