Pharaoh during Egypt's 18th Dynasty, Amenhotep established a monotheistic religion worshipping the sun god Aten, alleged creator of the universe. Some historians regard this as a predecessor of current monotheisms. Changing his name to Akhenaten, he established Aten-devoted cities in Egypt, Nubia, and Syria, attempting to obliterate all worship of the Egyptian Gods Helopolitans and Ennead. He moved Egypt's capital city from Thebes to the newly built Akhenaten. His priests secretly continued their polytheistic worship. At one point the mutant Apocalypse posed as Aten during a meeting with Akhenaten.
In 1334 B.C., after a 17 year reign, Akhenaten was abducted by the alien Cosmic Order, who had two millennia before discovered and accessed the vast power of the Heart of the Infinite. The Cosmic Order used their ultimate might to force peace onto the universe. They sought local humans to guide each space sector through this transition, and Akhenaten's ruthless leadership history and vision for the future made him an ideal candidate. For nearly two millennia, Akhenaten danced with insanity. His son succeeded him as Pharaoh, only to be murdered by General Horemheb, who eradicated all traces of Akhenaten and restored worship of the gods of old. Eventually acclimating to his cosmic role, Akhenaten earned the Cosmic Order's full trust and mastered the Heart's power over two millennia more.
Plotting to betray and conquer the Cosmic Order, Akhenaten returned to Earth in recent years, proclaiming himself its ruler and slaying opposition, including many superheroes and Godheads of Earthly pantheons. Even the cosmic Eternity and Infinity were blinded to Akhenaten's existence. Dr. Doom learned Akhenaten's origins, and traveled back in time to slay him before he gained power, but Akhenaten anticipated this and foiled him. The mad Titan Thanos, seeking the Heart of the Infinite's power for his own ends, teamed with the Defenders (Doctor Strange, Hulk, Namor the Sub-Mariner, and Silver Surfer) and Captain Marvel (Genis-Vell) to infiltrate the Cosmic Order's space station. Their secret revealed by the Hulk's rampage, they nonetheless located the Heart and severed the Order's instrumentation. Accessing and becoming one with the Heart of the Infinite, Thanos easily overpowered Akhenaten, leaving him to a vengeful Doom. Thanos then eradicated the Celestial Order's race in a past time period before they first accessed the Heart and pronounced him God, effectively preventing Akhenaten's assault on Earth and erasing his actions since encountering the Order. Thanos ultimately relinquished his new power to repair a terminal defect in the fabric of reality.
Note: Akhenaten is distinguished from the earlier Amenhotep, later a vampire in the Legion of the Unliving.