Henry "Hank" Henshaw appeared as the Cyborg Superman during the Reign of the Supermen storyline following the death of Superman. He has also been referred to as the Man of Tomorrow or, simply, the Cyborg.
Hank was a member of a doomed spaceflight on a LexCorp shuttle, where his body rapidly aged as a result of a space flight - a pastiche of the origin of the Fantastic Four. Before he seemingly died, he successfully saved his wife, a fellow astronaut on the flight, who had been fading from existence.
It was later revealed, however, that he survived as a consciousness able to manipulate computers and machinery, and had transferred himself into LexCorp's mainframe, and then into Superman's Kryptonian escape shuttle, which he used to explore the universe.
He returned as an incomplete Superman lookalike, with mechanical parts over large sections of his body, and blamed Superman for his exile. With Superman dead after his battle with Doomsday, the Cyborg claimed to be Superman reborn; DNA tests matched Superman's, and his technology was identifed as Kryptonian. Allied with the alien warlord Mongul, Cyborg was responsible for the destruction of Coast City (a prelude to Green Lantern's Emerald Twilight story). Naturally, Superman returned from the dead after a long, controversal period (this story also introduced the clone Superboy and Steel). He returned without his super powers, yet still tried to defeat his cyborg counterpart. Henshaw attempted to kill Superman using Kryptonite energy, but the Eradicator, an ally of Superman, intercepted the blast, at the expense of his own life. However, as the Kryptonite energy passed through the Eradicator, it re-powered Superman. Superman grabbed the Cyborg, stuck his arm through his chest, and vibrated his arm at a great rate, dispersing Henshaw's molecules. Henshaw managed to reform himself, during the Superman/Doomsday mini-series, the Cyborg returned, a result of succesfully installing a device on the back of Doomsday when he dispatched him into space. With Doomsday unleashed on Apokolips, the Cyborg seized the opportunity to try and take control of the planet, he was eventually stopped by Superman, Waverider and Darkseid, Darkseid delivering the killing blow with his Omega beams.
This however, did not kill Henshaw, as Darkseid had merely stored his consciousness in a small orb, with which to use whenever he needed. Henshaw soon found a means of escape when he was used by a galactic tribunal to help bring in Superman for crimes against Krypton, however, the Cyborg attempted to betray them, and when Superman was exonerated from the corrupted trial, the Cyborg was sent to an apparent death. He again escaped this fate, and briefly encountered Hal Jordan in his final days as Parallax, during the Final Night, at the very brim of the Godwave, a nexus of statues that flow fourth energy vital to the preservation of the fourth world. The Cyborg was imprisoned in the godwave by the souls and memories of all his victims.
During a crisis involving the Godwave, Superman (wearing at the time his "Blue Electrical Costume" travelled to New Genesis, and encountered Henshaw again, Henshaw had become part of the Godwaves' 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 had stored his own consciousness in Superman's suit and upon returning to Earth, the Cyborg split Superman into two beings before his next defeat, also setting off the events that led to Superman's rebirth as one being with his traditional powers and costume.
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 heir to 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.