Invincible Omni-Man first arrived on
Earth in the 1980s, where he eventually adopted the secret identity of a best-selling author named Nolan Grayson. He married
Debbie, whose life he had saved, and they had a son together named
Mark Grayson. In issue number 7, Nolan lures Earth's premiere superhero team, the Guardians of the Globe, to their hideout in Utah, where he brutally murders all the members. It was later revealed that the Immortal, the Guardians' leader, had been resurrected by the supervillain duo the Mauler Twins in an attempt to brainwash and control him. Remembering Omni-Man's betrayal, Immortal tracked down Nolan and battled him in public, outing him as the murderer and villain he truly is before being killed yet again. Nolan reveals that he was sent to Earth as a conqueror for the
Viltrum Empire, a revelation that was in stark contrast to his previous claims that his presence was to advance human technology and protect the Earth from extraterrestrial dangers. In a confrontation shortly thereafter, Omni-Man beats Mark to within an inch of his life, yet he refuses to kill him before he leaves the planet. It was further revealed that Nolan had found a new planet called Thraxa to rule over, in the hopes of offsetting some of the consequences of his earthly failure. Nolan's rise to power, however, was entirely peaceful. The custom of the native inhabitants, a race of mantis-like aliens, dubbed the Thraxans (an
insectoid people who live entirely within a nine-month span), was to simply choose the oldest among them to act as their leader. As on Earth, Nolan has taken a native wife, Andressa, and sired a second son, Oliver (who subsequently begins to use the codename "Kid Omni-Man" when he accompanies Invincible back to Earth). The genetic differences between
Viltrumites and the mantis-people were more apparent, though, than they were with humans. This caused the child to age much more slowly than his mother's species, but much faster than his father's. Omni-Man's attempts to appease the
Viltrum Empire ended in failure with his defeat and capture at the hands of his own people. He was held captive in prison until the Empire was able to send the required Viltrumite executioners. His parting words to Mark were "Read my books, Mark. My books..." In a conversation with his tailor Art Rosenbaum, Mark learns that the books Nolan referred to were not his well-known travel books, but a series of failed
science fiction "novels". While Art suspected that the stories were Viltrumite folklore, Mark quickly realized that they were, in fact, first-person accounts of Nolan's own missions to destroy potential threats to the Viltrum Empire, which could provide the secrets to defeating the Viltrumites. He is later saved on the day of his execution by Allen the Alien, to whom he agrees to reveal the "secret": Viltrumites are a near-extinct race, with fewer than fifty pure-blood able individuals left. Emboldened by the incredible strength shown by his new ally, he begins a two-men campaign to eradicate Viltrum's supremacy. Embarking on adventures across the galaxy, they gather weapons and allies which will give them an advantage over the Viltrumites, before returning to Earth to collect Mark and Oliver. They are briefly waylaid by the Viltrumite champion Conquest, an old enemy of Invincible who is killed in the ensuing battle, but not before Mark is critically injured. Nolan spends the subsequent months bonding with Oliver while Mark heals. In the final battle of the war, the anti-Viltrumite coalition is victorious, destroying the Viltrumite homeworld and scattering their enemies, although Nolan is badly wounded by the Viltrumite regent
Thragg, who secretly relocates the surviving members of his race on Earth, planning to interbreed with humans to covertly rebuild the empire. Tensions mount when Thragg discovers that Nolan is a descendant of the long-dead Viltrumite king, and thus heir to the throne, provoking a fierce battle between them. Although Nolan is overpowered, the Viltrumites recognize him and rally behind him, forcing Thragg to flee. Nolan is subsequently crowned as ruler of the Viltrum Empire. Nolan manages to overlook the Viltrumites on Earth and sees how the Viltrumites changed for the better and see Earth as their new home. Nolan learns that Anissa raped Mark, and is saddened at Oliver's death. In the final confrontation between the Viltrumites and Thragg's army, Nolan was fatally wounded by Thragg. In his last words to Mark, Nolan Grayson names Mark as his successor to be the Emperor of Viltrumites. In the future, his grandson (Marky) visits Nolan's grave and promises to live up to his father's legacy.
Dynamo 5 In
Dynamo 5: Sins of the Father, Omni-Man (alongside
Captain Dynamo, Supreme, and
the Savage Dragon) defeats Dominex in combat thirty years prior to the series' events, in which Dominex's three sons seek to regain their family's honour (after their father had been spared from execution and sent him back to his home planet in shame) by fighting Invincible and the
Dynamo 5. ==Powers and abilities==