Little is known about the true identity of the master criminal known as the Key. Obsessed with keys, the Key intended to become the "key" man in the universe by conquering first the Earth and then other inhabited planets.

Over the years the Key had injected himself with various "Psycho-chemicals", hoping to give himself psionic powers. Eventually he drugged Snapper Carr, honarary member of the JLA with a psych-chemical that would allow the Key to control him by electronic means. The Key then forced Carr to administer the psycho-chemical secretly to the rest of the JLA, whom the Key then ordered to disband.

The Key then intended to use the chemical to take over the minds of the worlds "Key" government officials and eventually force the JLA to help him conquer other planets. Thanks to Hawkgirl, the Justice Leaguers were freed from the Key's control and they captured him and sent him to prison.

Months later, the Key used the Psionic power the psycho-chemicals gave him to tap the cosmic energy collected in one of his weapons in the JLA trophy room. He used it to mentally force the Leaguers to kill each other. This time Superman thwarted the Key's scheme and the JLA stopped his next attempt at world conquest.

Eventually the Key discovered that the psycho-chemicals he had taken over the years were killing him. Failing again to kill the JLA, the Key retalliated by using cosmic energy to blow up a city block while he lay protected inan underground crypt. John Stewart (Green Lantern) drove the energy underground, where it unexpectedly cured the Key, but caused his body to become withered and dwarfish.

After another failed attempt to kill the JLA, the Key used the android Amazo to steal super powerful energy from several leaguers bodies, which he then used to restore his own body to normal. Although the JLA defeated the Key once more, Zatanna used her magic to return the Key to normal permanently.