The protagonists of the Metal Hero Series are mainly space and police-based characters who are typically androids, cyborgs, or humans that don "metallic" suits. Henceforth, most of the Metal Heroes are also referenced as "Henshin (transforming) Heroes." Usually, the genre revolves around a technological theme where technology, in the right hands, can be used for the greater good. Some of the Metal Hero Series even spawned sequels which followed the continuity of the previous shows, resulting in the genre developing sub-categories based mainly on space and police-related characters.