Little is known of the origins of the being known as Zanadu.  He was found encased in amber on a dig containing artifacts of the ancient land of Lemuria by archeologist Carter Hall and returned to the United States.  Zanadu later claimed to be the last survivor of the lost continent and had placed himself into the amber after absorbing the life forces of the populace.  Whether this is true or the ranting of madness is unconfirmed.

In 1976, Carter Hall had removed the amber cube containing Zanadu to the artifact room beneath his home.   He showed it to a colleague, Dr. Arthur Kliburn, who warned Hall that the being encased in the amber seemed evil.  In fact, Kliburn burned with greed at the recover of an actual being of Lemurian origin and return to the Hall residence that evening to steal the cube.  Instead, he found the amber melted and an awakened Zanadu, who promptly kills Kliburn.  The sounds of Kliburn's murder awakens Sheira Hall, who initially attempts to fend off the arcane being before attempting to flee.  She is captured instead and kept in stasis, believing he could use the reincarnated heroine as focus of emotional energy to increase his power.  Zanadu departs, leaving Kliburn's corpse and an after-imagine of himself and Shiera behind.

Returning home in his guise as Hawkman, Hall finds the aftermath of the Zanadu's escape and summons the Justice Society.  They track Zanadu to Tokyo, where he has been drawn to Japan's island nature as a reminiscent of Lemuria.  There he begins to paralyze and drain the life from the Japanese population until the Justice Society arrives and attacks it.  Standing atop a volcano, Zanadu fights Superman and Power Girl to a stand-still while WIldcat and Hawkman attempt to rescue the Japanese people.    Stymied, Zanadu takes Shiera and vanishes, reappearing over JSA headquarters.  The he is drawn into battle with Star-Spangled Kid and Hourman and initially proves unstoppable.  The presence of Zanadu awakens Dr. Fate, who had been mortally injured by Vulcan previously and was believed near death.  Zanadu frequently referred to himself as a "Chaos master". though whether his alliance with chaos is what roused the Lord of Order Nabu and restored Fate is not clear.

Once fully engaged and with the remaining JSA, Zanadu was effectively overpowered to lose control of Shiera, allowing her to be rescued.  As he prepared to unleash his full powers, Doctor Fate summons the reconstruction of his amber prison, returning Zanadu to the state in which he was found (All-Star Comics #61-63). 

Whether he survived or escaped is unrecorded.  Where the cube containing Zanadu was deposited, even if deceased, is unknown.