Constant noise. I'm not really "scared" of it but when there is a constant repeating noise like clicking or tapping in makes me want to curl into a ball and scream.
To add to this, a constant high pitched sound played in an instrument like a violin can really send shivers down my spine. Also what scares my is really weird but being pregnant with something supernatural and having it claw itself out of my stomach. Weird I know and I don't know why it springs to mind.