I've always been mildly obsessed with Polish movie posters in general, but the horror ones are some of the best:
That's
Rosemary's Baby and
Aliens, respectively.
And then there are some African (Nigeria and Ghana in particular, it seems) horror posters that are the other end of baffling (Thanks Ferox for turning me on to these). I don't even know what's going on:
I'd recommend a deep Google Image search on both of these; there's lots of insane, amazing stuff out there.