Ice on any surface where I have to walk. I will avoid going outside or walking in areas where there is ice. I remember going to Pittsburgh to look at a college and there was ice everywhere. I think that was the biggest reason I crossed the school off my list.
Knives also scare me, and I do have a slight fear of bees, but only because I'm allergic to them.
However, I can say with pride I am not scared of these things, and would love to have one for a pet:
really big spider