The Eradicator is a fictional comic book superhero (and sometimes supervillain) character having a recurring role in Superman stories published by DC Comics. Originally created as a weapon by an ancient alien race, he is over 200,000 years old and is considered an artifact of Krypton. The character was created by writer Roger Stern, and first appeared in Action Comics Annual #2 (1989).
One of the surviving aliens, known as the Cleric, took the Eradicator and left Krypton with a group of followers. Unfortunately, they died soon thereafter, as the Kryptonian genetic link to their home planet precluded their survival off-world. The Cleric kept the Eradicator for 200,000 years, until he encountered Superman on Warworld. With the device, the two exchanged memories, and the Cleric had a vision of Superman's death at the hands of Mongul. The Cleric wished to prevent this from happening, and the Eradicator transported them to his asteroid. He noticed that the device changed to protect Krypton's sole survivor, and they used it to heal their wounds, both physical and spiritual. When the Cleric gave the Eradicator to Superman, he rapidly aged and died as the link to the Eradicator extending his life was severed.
Professor Hamilton, who had previously examined the Eradicator, restored Superman's memory, and Superman then went into the Phantom Zone to stop the device. He encountered a projection of Kem-L and learned that only the House of El can control the Eradicator, but he first had to undergo a rite of passage. When Superman completed it, he commanded the Eradicator to shut down, and it complied.
The Eradicator returned in Superman: The Man of Steel #1 as an energy being. It tried to turn the Sun into a red dwarf (the type of star that Krypton once orbited), but Superman stopped it with help from Professor Hamilton.
The Eradicator returned again in Action Comics #687 (June 1993), part of the Reign of the Supermen story arc, as "the Last Son of Krypton." Having been recreated by the Fortress robots after Superman's demise, it created a body for itself based on Superman's, by tapping into the solar energy reserves of Superman's corpse and by creating an energy matter flux through which it was able to grant itself a pseudo organic form. This experience caused the Eradicator to briefly believe itself to be a Kryptonian: in fact, it had deluded itself into believing it was Superman himself.
During this time, due to its enhanced senses, the Eradicator had to wear a special visor designed to cut down visible light, since its eyes were particularly sensitive to it. As a humanoid, the Eradicator proved to be a more brutal version of Superman, who showed no hesitation in killing a potential rapist and brutally breaking the hands of a safecracker. However, after a fight with Steel, where the armoured man fought to stop the Eradicator from killing potential adversaries, the Eradicator began to reconsider his more brutal approach, temporarily relocating to Coast City before it was destroyed by Mongul and the Cyborg, the Cyborg nearly killing the Eradicator in an attempt to frame him for the attack. Returning to the Fortress only to discover that Superman had revived thanks to the Eradicator's use of him as a conduit, the Eradicator drained all the power out of the Fortress of Solitude, regenerating and changing the appearance of its humanoid body, its personality now altered to show a greater compassion for the human race. Returning to Coast City, the Eradicator joined forces with Superman, Steel, Superboy, Supergirl and Green Lantern to fight Mongul and the Cyborg and stop him from destroying Metropolis. The Eradicator was seemingly killed in an attempt to shield Superman from a lethal blast of Kryptonite-based fuel, fully recharging the Man of Steel's powers in the process as the Eradicator's mass somehow altered the kryptonite radiation to allow Superman to absorb power from the kryptonite.
The original Eradicator program was revealed to still exist in the Fortress of Solitude's computers and, following the destruction of the Fortress in Superman's battle with Dominus, the Eradicator program took the form of Kem-L, and again attempted to brainwash Superman. The David Connor Eradicator realized that the program was still active, and, when the Fortress Eradicator attempted to merge with the Brainiac-13 program to use the futuristic technology to recreate Krypton once again, merged with the remains of the Fortress to control it and take it from Earth.
The Fortress-Eradicator took the form of a gigantic Kryptonian battlesuit, and gained a form of multiple personality disorder based on his conflicting programming. When it learned of the "Krypton" Krypto came from, the shock to the original directive of Kryptonian purity was enough to bring this into control, leading to his hunting down the dog as an anomaly that should not exist. Superman held him in suspended animation in his new Fortress, eventually telling him Krypto's full origin once he had learned it himself.
Most recently, the Eradicator returned to his humanoid state of being. He wears a new outfit which, like the "Krypton Man" costume, is a combination of elements from Superman's costume and Kryptonian robes. He has gained the ability to sense beings that should not be in the DC Universe, such as Mr. Majestic, which may be related to his original programming against alien influences. In Superman #220 (November 2005), the Eradicator was seriously injured by an OMAC. He was said during the 2005-2006 miniseries Infinite Crisis to be in a coma at Steel's headquarters, Steelworks.
What distinguishes the Eradicator from other Kryptonians is his ability to manipulate energy. Eradicator has vast energy manipulation abilities, ranging from being able to absorb, convert, and release various forms of energy as powerful blasts from his hands or eyes. Also, after the Eradicator and Mr. Majestic fought, Mr. Majestic altered the Eradicator's programming to make him more aware. The full extent of his programming alteration is unclear, although it has been shown that he can sense beings and gateways from alternate realities such as the Bleed.