The most common phobia is arachnaphobia. Fun fact. I have that one. I also really hate deep water. Not swimming pool deep, but, the ocean. Even the thought of being over water thats miles deep, even if I'm not currently there, creeps me the hell out. I even hate it in video games, swimming sections in lakes and oceans. Only if I can't see the bottom though.
Oh and balloons. Can't explain that one, probably scared of the noise when I was a kid, now I just hate them in general. Kids parties are a nightmare for me.