A villain of awesome power, a renegade inventor--discoverer of "the most powerful metal on Earth" as well as a miraculous "strength serum"-- who, clad in a special armored suit of his own design, is impervious to bullets, can fly through the air, and possesses monumental super-strength equivalent to Superman's.
Operating from a subterranean hideaway beneath the main tent of the Farnham Circus , somewhere on the Metropolis waterfront, Metalo stuns the city with a series of spectacular crimes --including the theft of an entire mail car from the Metropolis train terminal, and an attempt to extort $5,000,000 from the city's businessmen by threatening to destroy Metropolis --until finally, in a climactic encounter with Superman, "the very mountains tremble and are rent asunder by the colossal battle of these two super-powerful opponents ...!"
Believed dead after plummeting into a yawning lava-filled crevice at the peak of the awesome battle, Metalo manages to cling to an outjutting rock and although thwarted in his evil undertakings, to survive (WF No. 6, Sum 1942: "Man of Steel versus Man of Metal!"). (TGSB)
(See also Metalo of Earth-2)