RZ is a complete mystery. Who is he? Where did he come from & what's his full name? Well, all of that stuff will be solved in the FAR future but not right now.
Fiction
He was said in Us hiring Robot X to destroy Ventro. He was also mentioned again in Misted Reaction & Total Misted Overload. He was mentioned in Misted Reaction when Mistrel said that RZ could of helped them escape. Then Misty mentioned RZ in Total Misted Overload when she was trying to get ammo for her cannon. She said "RZ was the weapons master. He could help me if he could.". That proves that RZ is real nobody knows where he lives. He's only seen once a year when he has a meeting with the villains. RZ was also proved to be the code name of one of Roy's robots.
Notes
He is kind of a parody of the Grand High Witch in Witches. Nobody has ever seen her but they know she exists. They see her once a year at a meeting.
Other Stuff
I'm serious. He is a parody of the Grand High Witch from Witches.