Garn Daanuth is one of the two sons of Calculha and Dark Majistra, separate from his brother and father after birth and raised by his mother as a follower of the Lords of Chaos. When Majistra plotted to use the Zodiac Crystals to bring a new age of magic with Garn's help, Calculha and the young Ahri'ahn (later spelled Arion) opposed their plan. When the young boy usurped control and banished his mother to Darkworld, his body was converted into energy in which Calculha merged onto a neighboring star.
The resulting sacrifice of Ahri'ahn when he usurped control had the uncanny side effect of draining the color of his skin, an act that reminded him of his mother's perceived death and instilled in him his hatred for whom he would learn was his brother and father. He would use his immortality to master dark magic and become one of Atlantis's most powerful dark mages and ancient evils in history.
Garn was created by writer Paul Kupperberg and artist Jan Duursema-Mandrake.
Garn first appeared as an ancient rival of Arion after his resurrection and plotted to kill the mage to extract revenge for killing his mother. After managing to conquer Atlantis due to his skills in manipulating a neighboring city-state and taking advantage of Calculha's grave condition, he learns of his true heritage after dealing a deathblow to the then-Sorcerer Supreme. Eventually, his evil reign in Atlantis is brought to an end by Arion and he makes numerous attempts at killing Arion and his friends, being subjected to being sealed inside Arion's being and various defeats by his brother's hands. After destroying the land in which Wyynde was raised in and yet another plot thwarted by his brother in which he used the magic he gained from Dark Majistra and mind control to turn Atlantis against their mage-hero, he is cosigned to being sealed away in Darkworld by his brother at Calculha's reluctant behest. Though sealed away, it would become apparent that Garn somehow escaped this fate though how was unknown. He would later have escaped Atlantis's destruction by placing himself in suspended animation and re-emerged later to fight against the Justice League of America.
In a special Teen Titans Spotlight issue, it would also be claimed by Garth's inner insecurities (in the form of Changeling) during his mental torture done my Mento that he thinks himself to be a descendant of Garn Daanuth, noting that Garth's very name is merely a corruption of Garn Daanuth and explaining his oddities such as his purple eyes.
Later stories and retcons would establish Garn to be included among agent of the Lords of Chaos. His fate after his demise would be changed, having become a dictator of a nation after losing his magical powers due to changes in Darkworld.
When the magic from Darkworld return, he is approached by Arion to withhold it once more though instead takes to opposing his brother once again. The consciousness of the cosmic being that makes up Darkworld itself would later choose him as his new protector in order to kill Arion, recognizing his desire to impede Darkworld's yearn to slumber in which would release the full brunt of old Atlantean magic once more and Arion having the power to do so. Though Garn attempts to use Powergirl's intervention to his advantage by holding her hostage, he is promptly defeated by the duo and merged by Arion into the consiousness of Darkworld. The resulting action makes Darkworld cosmic being in a eternal state between sleep and wakefulness, freezing all Atlantean magic on Earth to be used.