Chay-Ara and Katar Hol were law enforcement officers who crash-landed on Earth while pursuing a criminal. Their ship crashed in Egypt. With their spaceship damaged beyond repair, the couple adopted Earth as their new home. Using their advanced technologies, the couple made the barren land thrive. In gratitude, the people of that time worshiped them as gods and declared them King and Queen. As the rulers of Egypt, the couple set about bringing the benefits of Thanagarian rule to the people; building a strong empire and military presence that provided stability to the region.
Katar Hol's wife Chay-Ara wanted to bear his children, but he was to caught up in his work trying to restore peace to the human world. Chay-Ara then met Katar's friend Bashari, who was a military ally. Chay-Ara and Bashari fell in love with each other. The highest priest Hath-Set witnessed the affair and told Katar Hol about it. Katar didn't believe him. However, after seeing Chay-Ara and Bashari kissing, he wished them dead.
Hath-Set inferred this impulsive comment as an indirect order, which he set about to carry out. After finding Chay-Ara and Bashari dead, Katar felt it was his fault and drunk the poisoned wine, and died holding hands with his wife.
While the information presented in the DCAU is inconclusive, the story of Katar Hol and Joseph Gardner does match two of the incarnations of Hawkman in DC comics.