The Eradicator was a Kryptonian weapon of mass destruction. It did exactly what its name implied it did; the Eradicator sent out an electromagnetic wave that altered the brain activity of a specific species it was keyed to attack – within days, the Eradicator drove every member of the race utterly and horribly insane. Within a week, they had killed each other. Given its use, the Eradicator was use in cases of absolute last resort.
Those that survived the effects of the Eradicator were known to suffer mental damages, in which the Shi'ar had dubbed it as Siege Sickness. Symptoms include, in varying degrees: progressively worsening seizures, muscle spasms often progressing to complete loss of motor-control, and in many cases, total neurological breakdown, resulting in death.
The Eradicator was first used against an alien race that invaded Krypton's sister planet Argo. After the weapon was used and destroying the invading race, the Eradicator was discovered to have an unexpected flaw; it could automatically adjust itself to attack a new race after the previous one was gone. This horrible discovery was tragically learned when a retrieval party was sent to retrieve the Eradicator were driven mad. A robotic drone was then used to deactivate the Eradicator, before burying it deep below the surface of Argo. In the months before the Krypton-Shi'ar War, the Eradicator underneath Argo somehow was reactivated. By the time the Kryptonians realized what was happening, it was too late; every Kryptonian on Argo was dead. This incident became known as the Argo Tragedy.
Three Eradicators were also one of the main weapons used on Battlestation Sentrius. After the end of the Krypton-Shi'ar War, General Dru-Zod used an Eradicator on a surrendering fleet of Shi'ar ships. The incident left the survivors to suffer the effects of the Eradicator known as "Siege Sickness". As a result, General Zod was convicted for war crimes and sentenced into the Phantom Zone.
When a distress signal was detected coming from Argo, a team of heroes travelled there to investigate its source, with Android travelling to the planet in the Starjammers' ship to deactivate the Eradicator that was still present. Although they were able to recover Kara Zor-El - Argo's sole survivor - and a valuable Kryptonian artifact, the team were forced to flee Argo and reactivate the Eradicator when D'Ken tried to use the opportunity to steal Kryptonian technology.
In DC Comics, the Eradicator was created as a weapon by an ancient alien race before founding itself on Krypton and corrupted into Kryptonian hands. Its new mission was to preserve his ideal of Kryptonian culture by eradicating all others - and thus the device became known as the "Eradicator." In subsequent stories, especially in the Reign of the Supermen, the Eradicator creates a body for itself based on Superman's. Recently in the Reign of Doomsday story, the Eradicator sacrificed his life in helping Superman in defeating Doomslayer.