Sinister Symbionts Siphoning Supermen

Two documented techniques were employed to drain powers possessed by the Supermen, one which left him weakened and the other which potentially had far deadly effects. Interestingly, two pairs of deadly doppelgänger employed each of these techniques against their world's Man of Steel, very nearly leading to the demise of the Last Sons of Krypton. Although each counterpart used a a different technique against Superman than had the other!

The first technique is exposing the heroes to Green Kryptonite, the radioactive substance remaining from the planet Krypton. On Earth-One, the criminal cyborg Roger "Metallo" Corben was implanted with a Kryptonite "heart" with a two-fold purpose, to keep his cybernetic body alive and as a radiological weapon against the modern day Superman. On Earth-Two, the German soldier Heinrich "Atoman" Melch was injected with a Green Kryptonite serum which both empowered his superhuman body and as a radiological weapon against the golden age Superman.

A less common technique is projecting purple energy dampening radiation, coming from an extraterrestrial origin. On Earth-One, janitor turned criminal Raymond Maxwell "Parasite" Jensen was inadvertently exposed to radioactive material brought from outer space, and which Parasite then used against Superman which weakened him. On Earth-Two, scientist turned villain George "Metalo" Grant developed a purple ray projecting weapon which likewise weakened Superman. While Parasite employed his purple ray aura to transfer Superman's abilities to himself, Metalo developed a related super-serum from the purple radiation to grant Grant his Superman-like attributes.