|Affiliations:||April Moon Gang|
|Voiced by:||Eric Michael Cole|
When his friend Harold blackmailed Dr. Corso into using his weapons expertise on his gang, "Kneejerk" was outfitted with synthetic arms and legs. Chainsaws, capable of cutting through solid steel, could deploy from his wrists and knees. With these gadgets, Kneejerk could open safe doors, or create escape routes for his team. However, the chainsaw blades impaired his balance. During a fight with Batman, he fell, causing the saws on his knees to jam into the ground and break off. The piston he left behind brought Batman to doctor Corso.
When Batman traced the gang to their hideout, Kneejerk was the first to be subdued. Batman, who had found the override on the prosthetics, spiked them as Kneejerk had him cornered. With his forearms and lower legs falling off, Kneejerk fell and was unable to get up.