Are there any species of pets that terrify you?

I love dogs but I do fear loose dogs. I got a shepherd once from the shelter who was the sweetest dog but one time a friend from church came over and all of a sudden he went wild and went after her. Luckily she ran in the bathroom and slammed the door shut as I was trying to hold him back. It was very scary. The only thing we could figure later is that it was my friend's "time of the month" and somehow the dog sensed it and it had an effect on him. She had been over a couple of times before and this didn't happen.

So now I don't go out walking anymore, thinking some dog might be loose and also unpredictable and just not like the way I look or walk or whatever.