Cyborg Superman's History
Hank Henshaw first appeared as a crew member of the doomed LexCorp space shuttle Excalibur. Hank and the other three members of the Excalibur crew (including his wife, Terri) were exposed to cosmic radiation, resulting in the crash of their shuttle. As a result of the radiation exposure, the human bodies of two crew members were destroyed. However, their minds survived and they were able to construct new bodies out of pure cosmic radiation and bits of earth and the shuttle (homages to the Human Torch and the Thing, respectively). Initially, Henshaw and his wife suffered no ill effects from the radiation and the crew traveled to Metropolis, in the hope of using LexCorp facilities to cure their transformed crewmates. During a brief battle with Superman, the crew member now composed of radiation became unhinged and flew into the sun. By this time, Henshaw's body had begun to rapidly decay while his wife was beginning to phase into an alternate dimension. With Superman's help, Henshaw was able to use the LexCorp facilities to save Terri, but died immediately afterwords. The remaining member of the shuttle crew committed suicide using an MRI booth.
However, Hank Henshaw had not truly died. Though his physical body had expired, he was able to transfer his consciousness into the LexCorp's mainframe. Now able to control technology, Henshaw appeared to his wife in a robotic body; the shock of the shuttle accident, Henshaw's death and his bizarre rebirth was too much for Terri and eventually led to her insanity and death. By this point, Henshaw's electronic consciousness had begun to disrupt Earth's communications networks. Using NASA communications equipment, Henshaw beamed his mind into the 'birthing Matrix' which had carried Superman from Krypton to Earth as an infant. Henshaw crafted a small exploration craft from the birthing matrix and departed the planet.
Henshaw spent some time traveling between planets; bonding with local lifeforms to learn about the culture and history of various worlds. Over time, Henshaw became delusional and paranoid, believing that Superman had caused the deaths of himself and his wife, then driven him from the Earth. Arriving on a planet controlled by alien overlord (and Superman nemesis) Mongul, Henshaw learned of the Warworld and forcibly recruited Mongul as part of a plan for revenge against Superman.
Reign of the Supermen: The Man of Tomorrow
With Superman dead after his battle with Doomsday, Henshaw was unable to directly seek revenge against the man he had come to perceive as his enemy and instead sought to destroy Superman's reputation. To that end, the Cyborg claimed to be Superman reborn; using knowledge obtained from the birthing matrix to construct a cybernetic body with organic portions genetically identical to Superman and technological components built with Kryptonian alloys. Along with destroying a Superman memorial plaque in front of the Daily Planet, the Cyborg exiled Doomsday into space and defended the President of the United States from an assassination attempt. As a result of the latter incident, the White House endorsed the Cyborg as the 'true' Superman and he provided the President with a communications device. When confronted by Lois Lane, the Cyborg claimed his memory was "blurry" but he could see a "spaceship on a farm. The name 'Kent'", suggesting Henshaw may be aware of Superman's secret identity.
Henshaw's arrival as Superman was simultaneous with three others: John Henry Irons, the self-styled Last Son of Krypton, and the modern Superboy.
The Destruction of Coast City
When an alien ship appeared over Coast City, the Cyborg revealed his true intentions, attacking and severely injuring the Eradicator as Mongul's craft destroyed the city, killing millions. The Cyborg was then able to convince the White House and the public that the Eradicator had been responsible for the destruction of Coast City, turning the public against the Kryptonian. He also came within a hairsbreadth of killing the Eradicator in direct combat. After tricking and defeating Superboy, Henshaw set about preparing to launch a warhead that would convert Metropolis into a second Engine City. However, Superboy was able to escape and warn the resurrected true Superman, John Henry Irons and Supergirl of the Cyborg's plans. The quartet traveled to the site of the former Coast City where Superman, Supergirl and Steel confronted Mongul and the Cyborg while Superboy stopped the missile from destroying Metropolis. While Green Lantern defeated Mongul, the Cyborg lured Superman and the Eradicator to the Engine City main reactor and attempted to kill Superman with the Kryptonite that powered the engine. Henshaw attempted to kill Superman using a concentrated blast of Kryptonite radiation, but the Eradicator intercepted the blast at the expense of his own life. However, as the Kryptonite energy passed through the Eradicator, the radiation was altered and acted to restore Superman's powers. Superman was then able to easily defeat the Cyborg (partially due to the Kryptonite weakening the Cyborg's Kryptonian form) by vibrating Henshaw's body to pieces.
Cyborg returns
Before exiling Doomsday into space, Henshaw had installed a device on the monster to allow him to detect if Doomsday were to ever escape. After the destruction of his 'Cyborg Superman' body, Henshaw transferred his consciousness into this device, as Doomsday was "the safest place in the galaxy" for the Cyborg to hide. Doomsday was eventually brought on board a space cruiser and managed to escape, landing on Apokolips. Henshaw re-emerged once again, reconfiguring an exo-armored Apokoliptian trooper into a new body, establishing his standard appearance with long hair and red armor, and began to lay siege to Apokolips alongside Doomsday (although the Henshaw's body possessed Superman's Kryptonian DNA, Doomsday did not seem to perceive the Cyborg as a threat). The Cyborg successfully took over most of Apokolips, but was destroyed by Darkseid's Omega Beams after a short battle with Superman.
Apokolips and Beyond
Darkseid's attack did not kill the Cyborg; rather, the Omega Effect had stored Henshaw's consciousness in a small orb, with Darkseid planning to use the Cyborg against Superman at a later date. Darkseid eventually freed Henshaw, with the understanding that Henshaw was to leave Apokolips and never return. The Cyborg eventually aligned himself with an intergalactic 'tribunal', which was seeking to bring Superman to trial for the crimes of his ancestors. Henshaw assisted the tribunal in capturing Superboy, Supergirl, Steel and Alpha Centurion, who had been preparing to rescue Superman. However, the Cyborg betrayed the tribunal and attempted to conquer their planet for conversion into a new Warworld. Superman and his allies stopped the Cyborg's plan and, when Henshaw's involvement in the destruction of Coast City was brought to the attention of the tribunal, they found the Cyborg guilty of genocide and sentenced him to death. As an electronic consciousness, Henshaw could not be killed by normal means and was transported beyond the event horizon of a black hole, where not even energy could escape from the gravity.
Rather than being destroyed, the Cyborg was transported to the Marvel Universe, as seen at the beginning of the Green Lantern/Silver Surfer crossover. The Cyborg destroyed a planet in another attempt to recreate Warworld, attracting the attention of the Silver Surfer. Their short battle was interrupted by the arrival of Parallax, who had been tracking the Cyborg for some time, seeking vengeance for the destruction of Coast City. In the confusion, Henshaw managed to escape and was returned to the DC Universe by the end of the story.
The Cyborg would again encounter Hal Jordan, at the very brim of the Godwave, a nexus of statues that flow forth energy vital to the preservation of the Fourth World. Parallax used his powers to generate representations of the victims of Coast City, who tore the Cyborg's body apart. Jordan than dispersed Henshaw's consciousness into the Godwave and the Cyborg was once again seemingly destroyed.
During a crisis involving the Godwave, Superman (wearing at the time his "Blue Energy Costume" traveled to New Genesis, and encountered Henshaw again, Henshaw had become part of the Godwave's structure and had crafted a small world comprised of his memories, which he used to taunt Superman, after seemingly being defeated. However, unknown to Superman, the Cyborg stored his own consciousness in Superman's technological containment suit. After Superman returned to Earth, Henshaw escaped and eventually constructed a new body, posing as a substitute high school teacher in an attempt to become human again (even managing to convince Ashbury Armstrong that he possessed some goodness). However, in a fit of rage, Henshaw revealed his true identity as the Cyborg and this body was destroyed in a short fight with Superman. To escape detection, Henshaw stored his consciousness in a toy. This toy was later stolen by the Toyman, leading the two villains to join forces to kill Superman. To this end, the Cyborg designed a machine that would break Superman's energy form down into multiple components and beam them to different points in the galaxy, preventing Superman from reforming. A malfunction in the machine caused Superman to split into Superman Blue and Superman Red, the latter of whom eventually defeated and captured the Cyborg.
In a firm sense of irony, Henshaw shared with Superman a crossover encounter with the Fantastic Four, convincing Superman that Galactus was the true ravager of Krypton for a time, the result transformed Superman into the herald of the world devourer for a while. Galactus transformed Henshaw into an inanimate slab of metal after Henshaw demanded he be made his heir, and be made "perfect", since he was half-human, his reduction to this state, void of all human matter, was as perfect as the merciless Galactus could perceive.
He later attempted to take over Kandor, but this failed when he was defeated by Superman and sent to the Phantom Zone. Shortly after Y2K, Henshaw escaped the Phantom Zone and attacked Superman, who was suffering from Kryptonite poisoning at the time. He was defeated with the help of the Kandorians and sent back to the Phantom Zone, swearing revenge. However, he was not encountered on subsequent visits to the Zone.
Lost Lanterns and Manhunters
Henshaw eventually made his way to Sector 3601, to Biot, the homeworld of the Manhunters. He gathered many Green Lanterns who were previously thought to be dead, including Arisia, Kreon, Ke'Haan, Boodikka, Laira, and Chaselon, and used them as power sources for his new model of Manhunters, the Highmasters. However, Hal Jordan and Guy Gardner discovered his operation. Jordan and Arisia combined the might of their power rings with one of the Highmasters, destroying the organic portion of Henshaw's body and most of Biot.
The Guardians of the Universe believed that, during Henshaw's time in Sector 3601, he may have discovered one of their closely guarded secrets: the existence of the Multiverse.
Sinestro Corps
Henshaw remained in custody on Oa until he was freed, along with Superboy-Prime, by a strike force of Sinestro Corps members. He was brought to Qward, where he was made into a herald of the Anti-Monitor, along with Superboy and the Parallax-possessed Kyle Rayner.
Henshaw revels the only reason he has joined the Anti-Monitor is that he has been promised to a final death at the hands of the Anti-Monitor as a reward for helping the Anti-Monitor achieve his goals. A death he has longed for that none even Superman can seem to give him.
Henshaw and his Manhunters head to Earth to assist the Sinestro Corps in their attack. En route, Henshaw stops leading the Manhunters, which continue to their preprogrammed destinations. As he watches them go, he remembers everything that has happened to him; from their dreadful shuttle accident to his wife's suicide when she sees him in his robot form. He finishes this journey of his mind by going to his wife's grave. He digs her corpse out and rips it into two, shouting that all he wants is not to be with her, but for these memories to fade.
Meanwhile, Manhunters begin an assault on the JLA satellite. Hawkgirl, Black Lightning, and Red Arrow retaliate; however, all three are neutralized when Henshaw assists in the attack and he successfully tampers with the mechanics of the satellite core. As the satellite is thrown out of orbit, Superman appears, seemingly from nowhere, and engages Henshaw in battle. Their fight continues on Earth, while Sinestro transports his crew and his ship from the Anti-Matter Universe. At first Superman seems to have the upper hand, however after two punches, Henshaw strikes with great power and rage, punching him through the Statue of Liberty. By the end, Henshaw has Superman in a choke hold, thinking that the victory is near.
However, Superman was not alone. Power Girl and Supergirl came to Superman's aide, and managed to defeat the Cyborg Superman, later throwing him at Superboy-Prime. He commented that they almost managed to kill him that time.
When the Green Lantern Corps decides to detonate New Warworld and the Qwardian Central Power Battery of the Sinestro Corps to destroy the Anti-Monitor, Henshaw is trapped behind a shield and exposed to the massive explosion. Before he is finally killed, however, he is able to thank the Green Lantern Corps for their mercy in ending his life.
A small fraction of Henshaw's corpse was found after the explosion. The Manhunters confirmed that he had perished, but were confused without his leadership. Seeking the leadership "programming" of their grandmaster, the Manhunters funnel a massive amount of energy into the Cyborg Superman, and he experiences yet another resurrection, crying when he realizes he is alive yet again.
Revolt of the Alpha Lanterns
During the Brightest Day, he was seen working with the Alpha Lanterns, working to augment every Lantern, including Ganthet, into an Alpha. While doing so, Henshaw declares himself the Alpha Lantern leader. Hank later details that his purpose in dealing with the Alpha Lanterns is to alter himself, such that he will be mortal again. He begins experiments on the Alpha Lanterns to reverse engineer their cyborg attributes into humans. Despite killing several Alpha Lanterns, Hank is ultimately successful in devising a way to reverse engineer the some of the Alpha Lanterns. Before Hank can force Ganthet to perform his new surgery on himself, the Green Lantern Corps spoil his plans and destroy his physical body. Hank then tries to transfer his consciousness into Boodikka. During this attempted transfer of consciousness Boodikka overpowers Hank with willpower and cuts his essence in half, thus destroying Hank Henshaw.
Reign of Doomsday
However, it seems that even this isn't enough to be killed. While surveying the remains of New Krypton, Boodikka was attacked by Doomsday, seemingly unprovoked. However, when Supergirl and Batman got her to the JLA Watchtower, Doomsday quickly followed, revealing why he was attacking her - Henshaw was still alive. Taking over the Watchtower, the presence of Doomsday overrode Henshaw's desire to die, vowing to destroy the beast once and for all even with Batman and Supergirl stuck in the crossfire. With one mighty blow, Henshaw tore through Doomsday, ripping his body apart. However, Doomsday recovered and, to the Cyborg's horror, he became "Cyborg Doomsday", took over the Watchtower and vanquished Henshaw, kidnapping him and the arriving Supergirl in the process.