While I respect and acknowledge the legitimacy of bees/wasps/hornets/spiders/tick/lice (nasty) and their ascension from hell, I do believe that there is an animal that's more scary than that.
Freaking dolphins.
Not that they look scary, I can totally handle being near a tank of dolphins, but everything else about them. Its not the creepy "oh dear god, please don't touch me or be near me. Actually please stop existing because you're freaking me out" that makes dolphins the highest on my list. They murder for fun and are rape anything and everything that can come near them. People have found porpoise dead on shore after being beat to death by dolphins. For no other reason than for fun. And they would freaking play with the bodies after they were done murdering it. They also take a rather twisted delight in raping the hell out of everything. They're crazed sex machines. Think of every stereotype of the dolphins saving some poor person's life, and there's a matching story of dolphin rape. They do it to their babies, other animals, humans, anything.
In conclusion, don't go near dolphins. They'll mess you up.