Payback

Payback was a villain from Batman Beyond - at first he appeared as a large, muscular and mentally deranged vigilante in a similar style to Lock-Up from the original Batman: Animated Series: however unlike Lock-Up Payback's motives were to get rid of the problems of the youths who attended a help therapy group.

Payback's methods were brutal and Batman even noted to the vigilante's face that he was insane if he thought the youths really wanted revenge as a way of solving their problems - yet Payback didn't listen and attack Batman just as he did anyone else that got in his way.

Ultimately it was revealed Payback was the son of the man who ran the help therapy group - who had used a robotic suit to try and "fix" the problems of his father's group so he would have more time to spend with himself.