The origin of Shadow Supreme was never given an issue of it's own to explain but rather through a flash back to an imaginary issue. Shadow Supreme's origin is much like the origin of Bizarro, Darius Dax created a device that would create evil shadow duplicates of people when hit by a certain ray. This was first used when Supreme was in his teenage years and Darius was also a teenager. The conflict was brief but in the end, Darius was defeated, the machine was destroyed, and Shadow Supreme disappeared or so we thought but in later years Darius perfected his device and created the perfect Shadow Supreme who would not disapper when his device was destroyed and is more permanent. However history has a way of repeating itself and Dax's Shadow Supreme was once again defeated but this time imprisoned in the Hell of Mirrors in the Citadel Supreme.
Years later when Supreme returned from a "revision", Shadow Supreme along with Korgo, Televillain, Ant Slaver, Vor-Em, Optilux, and Sentinel escaped from the Hell of Mirrors from Billy Friday's portable TV that was accidentally left behind. Shadow Supreme wreaks havoc at the Citadel where he kills Radar (which was actually a Suprematon) and proceeds to attack Suprema. Eventually Supreme and the real Radar arrive to help Supreme to defeat Shadow Supreme. Radar mauls off Shadow Supreme's left arm to defend Suprema (to her horror). Shadow along with Korgo, Vor-Em, and Ant Slaver were apprehended at returned to the Hell of Mirrors.