Which movies do you think are, borderline defining, of the horror genre, yet they are the most probable to have slipped from your typical "horror afficionado"?

For example, my favorite subgenre is found-footage, but I only recently discovered "Hell House LLC", which I can safely say is a great representative of the genre.

What are your picks that you believe are almost unanimously considered great horror films, but have probably evaded many horror fans, due to distribution/release timing/language e.t.c.?