The Tangerine Dream thread a while back re Edgar Froese's death made me think of music that scared you. I can recall older mates when I was a kid myself telling tales about walking through the park in the pitch black on mushrooms listening to Tangerine Dream on a personal stereo. I can see why this would be a freaky experience but have never been particularly scared by the music of Tangerine Dream.
I would say the music that scared me most was listening to Reality Asylum CRASS when I was 12, not that they are a scary band but just that venom in the vocals made my neck hairs properly flex - you could feel the real hatred.

Have you even been freaked out / scared by music ?