OMAC

From HallsWiki

Standing variously for "One Man Army Corps", "Operational Metahuman Activity Construct", and "One Million and Counting", an OMAC is a normal human who has been infected with a nanotech virus, which supplants their normal thought process and grants them flight, armor, and various superpowers for the purpose of hunting down and killing superhumans.

OMACs were the focus of The OMAC Project, featuring heavily in the lead-up and development of Infinite Crisis. There is a current miniseries about the last OMAC.