I have a fear of the dark. I have a phobia that someone's always there.
Seriously, though, I am a bit scared of the dark. It's a fear that goes away if I have a weapon in my hands. For instance, doing midnight patrols in the military was a piece of cake, since I had an assault rifle with me. Take away my rifle, and my imagination kicks in. All those things I can't see, rocks falling down a small cliff when I turn around. Suddenly, everything around me comes alive. When I have a weapon in my hands, all that anxiety goes away.
I'm also quite afraid of dark water. Clear water, like at a pool or something, that's all cool and all, but if it's dark and muddy, I ain't going in there. How am I supposed to wrestle a shark if I can't see it? Never mind the fact that it's a lake inland, but I need my shark-wrestling crystal-clear water. Heck, even slightly visible will do.
Other than that, I'm pretty fearless. I don't mind heights, or wild animals. There's just one more thing that gives me these cold, deathly chills. Our unit's vice commander. The man's a demon, I tell ya. One look from him will freeze your blood solid. He's and all right person by all means, strict and fair, but he still has this barely contained, primal fury that he wears on his face at all times. He says "give me twenty" and we'll be stuck in this perpetual push-up mode where we're too scared to stop until he gives the word.