Overkill is a vigilante with cybernetic hands and eyes. Described by a City cop as a "robo-ninja", Overkill believes violence is always the best solution to any problem. His past is a mystery, but it is known that he was once an agent for the organization AEGIS until he somehow finally snapped mentally and went rogue; he admitted to having a social media account under the pseudonym GunSkull17, also looking at Arthur Everest's Reddit thread regarding the conspiracies about The Terror's survival. These days, he has a vendetta against The Terror himself, whom he also believes is still alive.
Before he became Overkill, he was once Uncle Samson's sidekick Straight Shooter and was traumatized from losing his team, eyes and hands.
After the crash of the flag five ship agent Tyrannosaurus Rathbone recovered him and had Dr. Hobbes create him artificial hands and eyes. Rathbone became like a father to Ty retraining him and having them placed in charge of the elite Perseus squadron. The team was assigned to a mission on Miami to apprehend a super tech dealer known as The Duke. During the mission, the entire team was killed with the exception of Overkill. Believing that he would be marked as a traitor he went on the run from AEGIS.
It has been suggested that he was a former love interest for Miss Lint.
Overkill is your typical masked gun-toting vigilante who punishes evildoers wherever he goes. However, his dark attitude frequently clashes with the more noble seeker of justice The Tick, and as a result, they often jab at each other. Like Arthur, he is implied to have an extreme version of obsessive-compulsive disorder (OCD) as seen in his fervent search for proof that The Terror lived through his last battle with Superian.
In Lei-Lo, Ho!, Dot and Overkill continue their mission to find the Duke, a villain who was responsible for killing Overkill's A.E.G.I.S team. The night before the mission, Dangerboat suggests that they do "the thing" because it is a character-defining, all-or-nothing, point-of-no-return type missions. After some convincing, Overkill agrees to do the thing which is revealed to be a dance party to celebrate their fight for vengeance.
- "We fight for vengeance, we fight for blood, we fight for the right to dance." (Lei-Lo, Ho!)
- He is probably based on Big Shot from The Tick animated series.