John Corben

John Corben was a criminal formerly known as Metallo.

History
John Corben was an unscrupulous reporter who worked in the Metropolis area. While driving his car, Corben was involved in a terrible accident and was nearly killed. His broken body was taken to the laboratory of Professor Vale who replaced Corben's failing limbs with a super-strong metallic alloy. He replaced his heart with a surrogate pump made of Uranium and covered the endoskeleton with a foam-latex sheathe resembling human skin. The operation proved successful, but soon after, Professor Vale suffered from a mild stroke.

Dubbed Metallo, Corben began his new life – a life of crime. Metallo's Uranium heart would only last for one day before it needs to be replaced, so Metallo began breaking into various facilities to steal more Uranium. Whenever he felt his Uranium stores running low, Metallo became weak and dizzy.

Corben got a job at the Daily Planet and began courting Lois Lane. Lois was enamored with Corben due to his physical resemblance to Superman – a fact that invariably irritated Clark Kent.

The recovering Professor Vale meanwhile, discovered that Kryptonite could work just as effectively at powering Metallo as Uranium, but with the added benefit that it would no longer need to be recharged. Metallo stole a Kryptonite rock from a local exhibition hall and had Vale implant it into his chest. Metallo learned that Kryptonite could also destroy Superman. Certain that Superman would likely try to arrest him for his recent crimes, Metallo decided to use the power of his Kryptonite heart to strike the first blow against the Man of Steel.

He baited a trap for Superman, but Superman managed to avoid exposure to Kryptonite and pursues Metallo. He chased him back to Lois Lane's apartment when suddenly Metallo began to feel weak. What neither Vale nor Metallo realized was that the Kryptonite that had been used to power his heart was actually fake. It was nothing more than an ordinary rock painted green to resemble Kryptonite. Unable to recharge himself, Metallo fell over dead from a heart attack.

Powers and Abilities

 * Superhuman Strength
 * Super stamina
 * '''Superhuman Speed

Weaknesses
Metallo's heart was powered by Uranium and needed to be recharged once per day.