Among the most powerful protectors of Earth-One was the age-old Doctor Mist, known to his former subjects as Nommo. Like Nabu the Wise of Earth-Two, Nommo was more a metahuman mastermind who meddled in the affairs of malevolent mankind from behind-the-scenes. Both Nommo and Nabu, despite having great powers, decided to use others as pawns to protect the powerless. One day, both would play influential roles in the lives of the Supermen of twin worlds.
Indeed, it was Doctor Fate aka Kent Nelson. Nelson, the heir to the legendary Nabu, possessed a superhuman physique matching any Kryptonian's. A longtime colleague of Earth-Two's Superman, this Kent also had a superhuman physique such as superstrength, invulnerability, flight, heightened senses as well as those abilities granted him by his mentor. A member of both the Justice Society and All-Star Squadron, Nelson was a heroic team player, both with and without the aid of his mentor Nabu.
Doctor Chaos, one of Earth-One Superboy's most powerful adversaries, was a Lord of Chaos from another dimensional plane just like the second Doctor Fate of Earth-Two, who originated in a composite post-Crisis Earth and was its protector from the notional realm known as Asgard. Chaos mentally controlled archaeologist Bert Belker, and terrorized Smallville until the Boy of Steel outsmarted him. Belker's own counterpart was the father of Kent, Sven Nelson, who perished when unearthing the tomb of Nabu. The post-Crisis Fate eventually left Earth-Two's Asgard, while Chaos ' helmet wherein his mind resided was exiled into space by Superboy.
Nelson was reacquainted with his alter ego after nearly two decades apart, and the original Doctor Fate once more returned to aid the Justice Society. Meanwhile, Nabu's doppleganger Nommo would finally appear once more on the world's stage around this same time, reaching out as Doctor Mist to his world's most prominent heroes, like Superman with whom he formed the Global Guardians.
Among Doctor Fate's most powerfully potent adversaries were Vandaemon and Ynar, who were former Lords of Chaos and Order respectively who reconciled and sought to control the Multiverse through their union. Their counterparts were a pair of adversaries of Earth-One's Superman, the estranged husband and wife known as Lord Satanis and Serene. The sinister Lord Satanis had conspired to split Earth-One's Superman in two with his wife and arch-enemy Syrene, with the goal of controlling her version of the Man of Steel for several decades. Similarly, Vandaemon and Ynar attempted to usurp control over Doctor Fate for their own evil purposes. In both instances, these devious duos were defeated.