Both Giant Robo and the Iron Giant are sentient giant robots who become the friends of young boys who can control them (Daisaku Kusama/Johnny Sokko and Hogarth Hughes, respectively), both of them were originally created to be weapons of mass destruction, and both of them willingly sacrifice their mechanical lives to save Earth in a similar way (they both fly up into outer space and collide head-on into a meteor and a nuclear missile, respectively) in their respective stories' endings.