Kzer-Za was a Green Ur-Quan, a scientist, during the time of the Dnyarri Slave Empire (20,000 to 17,500 BCE). It was he who found how to defeat the Dnyarri in discovering that the creatures would disconnect from a dying or seriously injured slave. The name of Kzer-Za is legend among both Ur-Quan subspecies as a martyred genius. The Green Ur-Quan named themselves in his honor. His research also led to the invention of the Excruciator by the Ur-Quan, a violent device that is implanted directly into the brain and causes constant, horrifying pain.