Japanese Giant Hornet (vespa mandarinia japonica)
It's the size of your thumb and it can spray flesh-melting poison. We really wish we were making that up. For, you know, dramatic effect. Because goddamn, what a terrible thing a three inch acid-shooting hornet would be, you know? Oh, hey, did we mention it shoots it into your eyes? Or that the poison also has a pheromone cocktail in it that'll call every hornet in the hive to come over and sting you until you are no longer alive?