I've said before that I think fantasy ought to be frightening. When I'm trying to get myself into the right frame of mind for presenting some horrific creature or scene in my campaign, I often think on images that frighten me. One of the ones that never ceases to give me the creeps is a spider descending on a thread. For some reason, that just sends shudders down my spine (above and beyond the simple fact that I am very arachnophobic -- even putting this image on the blog took some bravery on my part).
So, I'm curious: what images do you find frightening and yet inspirational?