Metallo

John Corben was the test pilot for Lexcorp's prototype military power suit, but was secretly an operative of Intergang. When Corben stole the suit, Superman fought him, destroying the suit and nearly killing Corben in the process.

Amazed and frightened that Superman had been able to destroy the power suit, Lex Luthor transplanted Corben's brain into his greatest invention, a robot made of a near-impervious alloy called Metallo.

To ensure that Superman would be unable to defeat this device, Metallo was powered by Kryptonite, a radioactive remnant of Superman's home planet. A chip in Corben's brain kept Luthor in control of his higher reasoning. To remain covert, a synthetic exterior provided the illusion that Corben was still just a man, but the illusion was only skin deep.

With no human sensation, Corben suffered a psychotic break, overriding the chip in his brain. He escaped from Lex's lab, seeking to destroy the man of steel.