OMAC (One-Man Army Corps) was a superhero comic book created by Jack Kirby and published by DC Comics. OMAC was a corporate nobody name Buddy Blank who was changed by an A.I. satellite called Brother Eye into the super-powered OMAC.
OMAC worked for the Global Peace Agency, a group of faceless people who policed the entire world using pacifistic weapons. The world balance was too dangerous for large armies, so OMAC was used as the muscle for the Global Peace Agency.
OMAC lasted for eight issues of his own comic, then became a back-up feature for Warlord. OMAC made appearances as a guest alongside Superman in DC Comics Presents. OMAC was revealed to be related to another one of Kirby's creations, Kamandi.
In 1991 OMAC was featured in a four-issue prestige format series by comic artist and writer John Byrne that tied up loose ends rather nicely.
Kirby had kept his run on OMAC well attuned to future events.
The character was recently rebooted in the DC Countdown , and will be starring in his own series in April.