Kryptonite

Kryptonite is a mineral from the Superman mythos, originating in the Superman radio show series. The material is usually shown as having been created from the remains of Superman's native planet of Krypton, and generally has detrimental effects on Superman and other Kryptonians. The name "Kryptonite" covers a variety of forms of the substance, but usually refers to the most common "green" form. The word Kryptonite is also used in speech as a synonym for Achilles' heel, the one weakness of an otherwise invulnerable hero. A forerunner of the kryptonite concept was the unpublished 1940 story "The K-Metal from Krypton", by Superman co-creator Jerry Siegel. The K-metal in the story was a piece of Krypton which robbed Superman of his strength while giving humans superpowers. "Kryptonite" was introduced in 1943 on the ''Superman'' radio series, as both a plot device and to allow Superman's actor, Bud Collyer, to occasionally take time off. The substance played a part in at least one... full article at wikipedia