John Stewart was a former superhero turned rogue in the Justice League series.
Much like his main counterpart, he was in the military and became a Green Lantern. This all changed when Lex Luthor became president and executed the Flash. In response, Superman killed Lex Luthor in the Oval Office and the Justice Lords took over the world. John Stewart traded his costume for a new one when the Justice Lords brought peace through tyranncy. At some point, he shaved his head bald and progressed in his relationship with Hawkgirl. Green Lantern discovered an alternate universe through Batman. He like the other Justice Lords discovered alternate versions of themselves still as tsuperheroes with an alive Flash.