I have such a complex with (Grand) Daddy Longleg Spiders.
Nobody believes me when I try to tell them, but when I was about four-years-old or so, I saw my first one in the garage, and I SWEAR THAT THING WAS HUGE! It's body was about the size of a small baseball, and it's leg-span spread out was large than a hula hoop! I WAS FREAKED OUT! To this day, I STILL can't even get near one of those things without having an anxiety attack.
As for official phobias, I have mild claustrophobia.