Created by Kevin Smith in 2007, Onomatopoeia was meant to be a supervillain that could only exist in comics. The reason for this was because he has the ability to perfectly mimic the sounds around him, making him somewhat invisible to one who is merely listening for him to arrive.
Also though, Onomatopoeia is a skilled martial artist, athlete, and capable with numerous weapons, including knives and guns. He specifically goes after foes with no powers, as to help prove how good he is. He's gotten the drop on both Green Arrow and Batman, and has even tricked Batman into letting him into the Batcave, and gaining his trust to the point where he unmasked himself in front of Onomatopoeia.