Humans.

When I read some of the other writer's block answers, I noticed that several people answered the same as I did. Humans, people, mankind.. the answers reasoned that they were truly scary because of their ability to hurt, apathy, rejection, etc.

That's not my reason. People just scare the hell out of me. I get social anxiety from the oddest things, and it terrifies me to no end. I can go to a concert with thousands of people attending, talk to random strangers in line, and fight my way through the mosh pit - but looking someone in the face who's walking down the same sidewalk as I am is difficult.

Besides people, the other animals I'd add are wasps/bees/hornets and cockroaches.

Why?

I didn't understand my fear of things that buzzed and stung for quite some time. I was finally able to trace it back to a childhood event. Also,  a wasp flew down my shirt and into my bra once. Talk about awkward/scary. I believe that was the first time I cursed in front of my mother.

And the cockroaches. Yes, they're disgusting and look weird. But the main thing about them is that YOU CAN'T KILL THEM! They've survived for so long.. I mean, anything that can withstand whatever killed the dinosaurs is pretty scary indeed. They move SO fast on their creepy little legs, and dart around and hide before you've even raised whatever you were going to squash them with. I had a childhood event with one of these, too. *shudder*

Things that didn't make my list, but made others:

Horses. Yes, they're big, smart, and easily crush me and/or break several of my bones. But so could a car. :) Plus, they're cute.
Snakes. I've always wanted a pet snake. I very nearly bought one last fall. I was shopping around for one, and came home to my mother one day to say, "I looked at a snake today in a pet store. It bit me. I want it." Call me crazy.
Spiders. They just don't scare me for some reason. The exception to this would be ones I know can kill me, like Black Widows and Brown Recluses.
Sharks. Yeah, 'cos I'm ever going to go deep sea diving.
Sloths. I could easily outrun one. Excuse me - outwalk.
Bugs. I play with bugs.
Birds. Maybe if I were covered in raw meat, and thrown into a cage with several birds of the raptor family that hadn't eaten in weeks..
Moths. They're completely harmless, and there are some varieties that are actually quite pretty.