HISTORY: Millions of years ago, the race of alien super-scientists known as the Serayn sought to learn everything they could about other races. Physically incapable of leaving their own world due to their extremely fragile bodies. the Serayn built an indestructible spaceship controlled by an artificially intelligent supercomputer. For a crew, the Serayn created the Undying. artificial creatures of pure intellect and energy, and gave them the power to meld their energy fields with the minds of any other living creatures. Once an Undying controlled a host body, it could only be released by the host's death, feeding off the energy thus released. The Undying ultimately proved to be the Serayn's downfall, as they were created with no sense of morality. They turned on their creators to feed their unquenchable thirst for death, and then set off into space. For millions of years, the Undying roamed the universe, devouring the death energies of numerous alien life forms; however, the Undying ultimately grew tired of this, and so began a contest to be judged by Azazel, their ship's computer, wherein whichever Undying killed the most life forms, won. Each match would last ten thousand years, or until all life on the designated world was exhausted. To keep the game fair, the Undying granted Azazel the power to transfer their energy matrixes from one host body to another at the moment of death, thus ensuring that no one Undying could gain an unfair advantage over the others.

The Undying 's ship eventually landed on Earth, starting a new contest. Over the centuries, the Undying mentally controlled numerous individuals and embarked on killing sprees. The more they slaughtered, the stronger they became. In modern times, the Undying Semijan possessed Australian mutant Randall Shire, a projecting empath, able to transmit his emotions into nearby people upon speaking. Semijan's presence boosted Shire's mutant power to astonishing levels so that Shire's voice bound people to him whenever he spoke Shires mutant allies Key and Wall became his first victims, followed by thousands more Australians. With Shire's power under its control, Semijan became ambitious and compelled Shire to travel to the U.S. and enslave high-ranking government officials, such as S.H.I.E.L.D. Commander G.W. Bridge, in order to seize control of America's nuclear arsenal. With the competition now unbalanced, Azazel sought to stabilize the game by using another Undying as Semijan's executioner. Thus, Semijan's fellow Undying Aentaros possessed a human father and drove him to attempt to assassinate Shire. The mutant soldier Cable foiled the attempt; however. Aentaros tried again by possessing the mutant mercenary Blockade, whose mind Cable had wiped earlier. Defeated, Aentaros forced Blockade to snap his own neck, thus freeing Aentaros to possess Cable's friend Irene Merryweather. Cable drove Aentaros out of Irene's body by telekinetically causing her to suffer a brief cardiac arrest. The Undying fled, leaving Irene to be revived by paramedics whom Cable had telepathically summoned earlier. Cable then learned that if Shire were to survive, a future in which humanity conquered the galaxy and became the Ranshi Empire would flourish. If Shire died, a future in which Earth became a peaceful paradise known as Harmony would occur.

Aentaros next possessed Cables mercenary ally Domino and compelled her to attempt to assassinate Shire, but Cable again foiled the attempt, preventing Aentaros from killing Domino as well. Semijan's anger at Aentaros was subsequently broadcast by Shire's powers, thus breaking his hold over those he had influenced. By preventing Shire's death and then discrediting him, Cable prevented both the Ranshi and Harmony futures from occurring in Earth-616's timeline. Subsequently, Cable enlisted the aid of Key, Wall and his X-Men teammates Beast and Jean Grey in confronting the Undying in their spaceship, which had been discovered entombed in the Sinai desert. There, while the heroes clashed with the Undying, Key reprogrammed Azazel to allow the Undying to possess only the bodies of cockroaches for the rest of eternity, thus ending their millennia-long threat.

NOTE: The above information was copied from “All-New Official Handbook of the Marvel Universe #12”