Involvement in the Mafia
Nicholas Rocca was born a troublemaker. Raised in Palermo, Sicily he started his life of crime at a young age, by young the age of 13, he was extorting protection money and selling his talents as a leg breaker. Then at 15 years of age, he caught the eye of Sicily's top boss of organized crime, Luciano Bartino. Bartino took Rocca under his wing and began training him to channel his strength and violence.
Destruction & Rebirth
During his life with the Mafia he became one of their greatest assets and quickly became known to the community. However during one of his many rampages, Nicholas killed the son of the Mafia boss Vito Calogero. Calogero was a longtime rival of Bartino, was enraged and made plans to call a hit on Nicholas. Calling in favors from oil-rich Arabian friends, Calogero had him ambushed. The Arabs shredded Rocca and left him for dead. Clinging to life, he was found by Bartino's men and brought home. Meanwhile, while in Sicily on business, Antonio Twistelli, the crime boss of New York, suggested Bartino try to make a Mafia super hit man like they did once with the failed Tremor experiment. This time they would have a willing patient in Nicholas. The experiment in the paramesh system went far beyond their expectations. Nicholas's body and mind embraced the operation fully. That night he became the one and only Overtkill. Bartino began loaning Overtkill's services out for favors to be named later. One such loan was made to Twist, who brought Overtkill to New York City to get rid of a problem, Spawn.
During his time in America, Overtkill found and attacked Spawn. It was the toughest battle Spawn had dealt with so far. If not for a mechanical oversight with Overtkill's circuits, Spawn may have died. Overtkill was the first one to defeat Spawn. In a later rematch Spawn found and destroyed him using some of Wynn's government weaponry. Twist rebuilt him and once again sent him to destroy Spawn.
Once again he was on the verge of success when Sam Burke and Twitch Williams intervened and managed to disable his circuits leading him to go find the only other to defeat him, the Youngblood member Badrock.
Overtkill had once been hired to destroy the Youngblood team but was humiliated when he was defeated, his reputation never recovered. Now with his circuits disrupted he went on a search for Badrock. The ensuing battle left him in pieces on the streets of New york. Once again Badrock had triumphed. But Overtkill's life was far from over.
Overtkill was also known for fighting Supreme although this battle led to yet another defeat and body.
Overtkill was reborn yet again when his own brother rebuilt him and dubbed the newer, larger and definitely more dangerous cyborg Overtwar. With his new body he set out on a search to find and destroy Spawn. Unfortunately for him, Spawn had grown much more powerful since their last meeting. He didn't even need his guns to kill him. In a quick fight Spawn decapitated the cyborg then interrogated it. After he got what he needed he left Overtkill to rot. He has yet to be heard from again.
Overtkill was originally called Overkill. It was changed because there already was a character named Overkill in Marvel's "Guardians of the Galaxy".