1. Death - some might call it rational but mine isn't. It's to the point of, if I thought of it enough, I'd go into hysterics.
2. Bugs - anything smaller than a mouse scares the bejeezus out of me. Bugs that can fly are the worst.
3. Being paralyzed completely but being conscious - I know I don't indulge in many activities that would lead me to this but the thought of beign trapped ina body without being able to move or speak but feeling and knwing everything that's going on around me? Again, the bejeezus thing.
4. Torture - weird, huh? If I am ever kidnapped, I'd rather be killed outright than be tortured. Which is a biggie because death scares the crap out of me too. This probably stems from all he serial killer novels I've read and movies I've seen.
I can't think of any more but this list might grow.