Onomatopoeia

Origin

A complete mystery, the man known as Onomatopoeia first appeared within the pages of Green Arrow. After killing two lesser-known vigilantes, he set his sights upon the Arrow family, seriously injuring Connor Hawke. He later tracked his prey to the hospital to finish him off, but was stopped by a blood-transfer weakened Oliver Queen. After Connor's successful surgery, Onomatopoeia fought the elder Green Arrow, doing quite well despite being hit with several arrows. Despite falling from the hospital roof during the fight, Onomatopoeia was able to escape before Green Arrow even had a chance to see where he had fallen.

Unseen for some time, Onomatopoeia, for reasons unknown, assisted the Joker in escaping Arkham Asylum as bait for Batman. He also shot Deadshot point blank in the head but was unsuccessful, overlooking Deadshot's ability to play dead. Onomatopoeia paid Joker to start a gang war against Maxie Zeus who was using Joker's laughing gas as a drug called "giggles". Eventually Onomatopoeia fought Batman in an hand to hand fight and lost, he escaped by stabbing the Joker in the heart and leaving Batman to choose either to capture him or save Joker. Batman decided to save Joker's life instead of chasing after Onomatopoeia. 
 
Not much is known about his past except his alternate identity has a family and his house has a secret trophy case with the masks of all the super heroes he's killed on display.

Skills and Abilities

His martial arts skills are quite formidable. He may have meta-human endurance since he was able to fight with several arrows lodged into him.

Onomatopoeia speaks only in sound effects, however he has spoken one actual word before, that word being "onomatopoeia". He said this word when a dieing superhero ask him "who he was" but she never heard it since he shot her before he said it.