John Henry Irons was an engineer that worked for the United States Military. He designed Metal-Zero for the Steel Soldier Project as a defense against the possibility of alien invastion. However, he quit the project when Lex Luthor captured Superman and tortured him.
When the Collector of Worlds attacked, John saw it on TV and decided to put a suit he had created to good use. Irons used the suit to stop John Corben, under the Collector's influence, from attacking Superman. However, Corben's suit has a faster processing capability and seemed to have the upper hand against Irons. The tide turned when Irons revealed that he had designed Corben's suit with an external USB port as a fail-safe. While they were fighting, Irons plugged in a flash drive with an autoloading virus, which crashed Corben's motor systems. Irons smashed him across the bridge with his hammer and the Collector of Worlds withdrew from the suit. However, he was surprised when Corben disappeard with a huge chunk of the city.