Kryptonite is a fictional material that appears primarily in Superman stories published by DC Comics. In its best-known form, it is a green, crystalline material originating from Superman's home world of Krypton that emits a unique, poisonous radiation that can weaken and even kill Kryptonians. Kryptonite radiation can be transmitted through any element except lead. Thus, Superman has a special lead suit to protect himself from the radiation. There are other varieties of kryptonite, such as red and gold kryptonite, which have different but still generally negative effects. Batman, Lex Luthor, Metallo, and Titano are four notable characters often presented as using kryptonite — the first carrying the substance as a last-ditch method to stop his ally (often at Superman's urging to take such precautions) if he is subject to mind control or otherwise compromised, the next two using the mineral to ward off Superman or incorporating it into weapons, and the fourth being able to project rays of kryptonite radiation from his eyes after being altered by simultaneous exposure to kryptonite and uranium. Due to Superman's popularity, kryptonite has become a byword for an extraordinary exploitable weakness, synonymous with "Achilles' heel".

History

An unpublished 1940 story titled "The K-Metal from Krypton", written by Superman creator Jerry Siegel, featured a prototype of kryptonite. It is a mineral from the planet Krypton that drains Superman of his strength and gives superhuman powers to humans. This story was rejected because Superman reveals his identity to Lois Lane. The mineral kryptonite, not to be confused with the real element krypton, was first officially introduced in the radio serial The Adventures of Superman, in the story "The Meteor from Krypton", broadcast in June 1943. An apocryphal story claims that kryptonite was introduced to give Superman's voice actor Bud Collyer time off. This tale was recounted by Julius Schwartz in his memoir. However, the historian Michael J. Hayde disputes this: in "The Meteor From Krypton", Superman is never exposed to kryptonite. If kryptonite allowed Collyer to take vacations, that was a fringe benefit discovered later. More likely, kryptonite was introduced as a plot device for Superman to discover his origin. On the other hand, Hayde might have mistaken 1945's "The Meteor of Kryptonite" for 1943's "The Meteor from Krypton", as Superman was exposed in the former but not in the latter. In the radio serial, Krypton is located in the same solar system as Earth, in the same orbit, but on the opposite side of the Sun. This provided an easy explanation for how kryptonite found its way to Earth. In the comics' Silver Age, which places Krypton in a distant solar system, much of the kryptonite that came to Earth was transported by the same "space warp" that baby Kal-El's rocket traversed. Kryptonite was incorporated into the comic mythos with Superman #61 (November 1949). Editor Dorothy Woolfolk stated in an interview with Florida Today in August 1993 that she felt Superman's invulnerability was "boring". Long said to be an element in the Golden, Silver, and Bronze Age comics, Kryptonite became a compound post-Crisis as revealed in Action Comics #591.

Forms, effects, and other media

Various forms of the fictional material have been created over the years in Superman publications and programs.

In popular culture

Music