The Horror Challenge,
Doesn't seem to scare other people as much as it scares you.
I have to choose Dead Silence for this one, since I was absolutely terrified when I watched this for the first time. I watched it with quite a few people actually, and nobody thought it was scary, except for me. It is one of my favorite horror films though, because it's one of the few movies that scared me, but that might also be because I'm absolutely terrified for clowns and dolls.