Blackguard was an unknown common criminal recruited by the 1000 and given his powers. His career proved less than acceptable to his new masters, particularly when he clashed with Booster Gold. Finally, the 1000 planned to execute Blackguard at the same time as they were planning to kill Booster. With the assistance of the Thorn, Booster and Blackguard both escaped death at the hands of the 1000.
Blackguard would later join the Suicide Squad. He lost a battle with the White Dragon in a training exercise. When The General began his betrayal, he grabbed Blackguard by the neck and popped his head off.
Blackguard has super-strength and wields an energy mace and shield. The energy mace and shield are similar to something a Green Lantern would make, including the color.
Blackguard is being played by Pete Davidson in the movie The Suicide Squad