Honestly? Quite a lot of things. But usually I don't let it control me. That said, my fears affect me a little to much in smaller ways...
I don't like not knowing where anybody is. In both the metaphorical (what their stance is on things) and physical (In the dark basically) sense. It derails my thinking process, cause I'm so used to at least having something to hang on about the person. Which is why things like Alien invasions, where their technology can be unknown, scares the living **** out of me. The only reason why I can even watch those movies is because I know the humans almost always win. After the movie, I have terribly bad relapses about it.
Everybody turning on me when I don't expect it (Sometimes when I do expect it...) This one, I've figured, is mostly a no pass. It doesn't matter now because I've forced myself to accept there's reasons for every action, no matter how stupid or cruel. It usually makes me more angry then scared. Still, the idea scares me. espcially when you put it out of the human's control...(like Zombie Apocalypses.)
A Problem I can't fix... It really has to be something i can't fix or even think I can fix. It has to dig deep. Or else It actually excites me.
...but the idea of a problem I can't fix still scares me. I don't like it, which is why I try my hardest to fix it or find a small solution.
Honestly, I don't really have any "Unnatural fears". Or I guess I could say I don't really have any "Phobia's" that make me turn into a screaming scaredy-cat. But a lot of things do have an effect on me...And they pile up a lot because i think to much. That said, I'm still a positive guy :X xD