Few things scare me. Most of the ones that do are well justified and not irrational.
Heights was one, I used to be TERRIFIED of heights, I climbed telephone poles doing cable work until it was manageable. When I feel from the top of one and landed on my back in the middle of the street (and it didn't kill me) I got over it.
Water was another. I grew up, literally a couple of hundred feet from the ocean. By the time I was 8-10 years old, my mother (trying to protect me, "Don't go near the ocean, you'll get pulled under and you will drown!") had gotten me to the point where I was terrified of water. To the point I wouldn't let go of the side on a 4' deep pool.
When I was about 11, a family friend who was professional lifeguard took me out on a lake in a canoe, and threw my ass into the water. I learned to swim. Quickly. Haven't been afraid since.
The craziest one is probably my irrational recurring dreams of a zombie outbreak... That's probably the only crazy one I have, and probably the only irrational fear I have left.