Ok, anybody who even reads manga or watches anime a little has to have heard of Gundam. For those who haven't, Gundam is about big giant robots piloted by people. Often the wars are between the Earth and the Space Colonies, although it can vary greatly throughout each series on who's fighting whom (take for instance, Gundam Wing, where the Gundam pilots are considered outlaws by the colonies they are fighting for, and are forced to fight for people who hate them).
Mind you, my knowledge of Gundam is much more limited in comparison to my knowledge of DBZ, so bare with me if I make errors in discussions.