Inheritor was created by Will Magnus. Inheritor was created when Magnus left the Metal Men believing they were treated more like property than living beings with thoughts and feelings. Inheritor is a Syntho-Rob 1 liquid plastic robot that was believed by Magnus to be superior to the Metal Men.
General Caper believed that Inheritor was to be used by the U.S. military as they perceived since the project was being financed by them.
The Inheritor was short-circuited by Mercury. He has not been since his first encounter with the Metal Men.