One of the god-like Lords of Order, Nabu took corporeal form and settled down in Ancient Egypt, where he became known as a court magician to several Pharaohs, including Khufu. During his time in Egypt, Nabu tried to warn the Pharao and subsequently his son against pursuing the escaping Jews, led by Moses. Failing that, Egypt was ravaged by the Spectre, who would not be bound to a human host before the time of Jesus Christ. Nabu attempted a direct confrontation, but was repelled. In 1940, Nabu (kept in suspended animation) was wakened by the young Kent Nelson, the son of archaeologist Sven Nelson. Nabu transformed Kent into a full-grown man and taught him the magic of Order, then gave Kent the golden Helmet of Nabu and Amulet of Anubis.
Kent as Doctor Fate
When Kent wore the Helmet, Nabu was part of him, and together they became the mystery-man called Doctor Fate in the 1940s. Later, Kent found Nabu to become possessive of him, and created a half-helm to wear instead. During this time, Dr. Fate would have less power but was no longer influenced by Nabu. Kent again joined Nabu during a clash with Kulak, after which the Helmet was lost. It would not be until the early 1960s that Kent would recover the Helmet and become the "complete" Dr. Fate again.
Eventually, Kent grew old and retired to another dimension. Nabu found new disciples, first in Eric and Linda Strauss, who together became the new Fate. During this time, Nabu was banished to Earth for having prevented the age of Chaos, and took residence in Kent's old body, enjoying life as a human. Later, Nabu created still another Dr. Fate by returning Kent to youth and merging him with his wife Inza.
After this, Nabu was reincarnated as the child of Eugene and Wendy DiBella, themselves reincarnations of Eric and Linda Strauss. Still later, Kent and Inza died and Jared Stevens ( Fate) was chosen as the new Fate. Nabu returned and wanted to use Jared the same way he had used Kent, but Jared refused. Nabu grew mad and sabotaged the then-current "treaty" between Order and Chaos. As punishment, Nabu was turned into a Lord of Chaos. Recently, Hector Hall became the the last in line of the Fate legacy.
Nabu returned again, seemingly with his senses back. Currently, Nabu is a free spirit in the world of the Amulet, whispering to Hector through the Helmet. His presence has become increasingly oppressive, however, and Hector is suppressing him as much as possible.
Nabu was the last of the Lords of Order and Chaos (save Mordru) to be slain by the Spectre before the Infinite Crisis, as a part of Alexander Luthor's plant to recreate the pre-Crisis Multiverse. The plan was to have magic broken down into a more primal form, making it more chaotic, to do it he had Eclipso's Black Diamond prison left in the asylum cell of Jean Loring to become the new Eclipso. As Eclipso, Jean would entice the host-less (and therefore easilly manipulated) Spectre to engage in a war on all magic, claiming it to be an abomination against God. Nabu however already knew the results the Spectre would yield and as the last remaining Lord of Order, he faced the rampaging Spirit of Vengeance. Ulitmately he was mortally wounded, but the Presence finally took notice of its servants dealings and ended the Spectre's war by forcing it to choose a new host in the guise of Crispus Allen, who wouldn't take the job for a year. Nabu, in his final act, told the mage's present that the Tenth Age of Magic would begin with his passing, as predicted, before he passed the Helmet of Nabu to Detective Chimp in hopes that they would find a worthy successor to the mantle of Doctor Fate.
Nabu, in the Kingdom Come universe, does not require a host and is able to is able to channel his consciousness through the helmet and cloak. Nabu sides with Batman and is apart of Batman's Legion. He teleports Batman's Legion to help Superman's Justice League. He is one of the surviving heroes.