History:  (Avengers I#187 (fb) - BTS, Thor I#301 (fb) - BTS, Thor Annual#10, Silver Surfer Annual#2/7, Doctor Strange III#11/2, Conan the Barbarian I#245 (fb) - BTS) - Atum is the off-spring of the female Elder God known as Gaea and the Demiurge, the sentient life-force of the Earth’s biosphere. Having infused her life-force into the planet, Gaea gave birth to Atum who began slaying all the Elder Gods who had degenerated into demons and were killing each other to survive and gain power.  Despite driving many of them to other dimensions, he absorbed so much of their energies that he transformed into Demogorge and left the planet to extinguish their absorbed energies.

(Iron Man Annual#10/4 (fb) ) - Gaea realized that for the mammals to survive, she had to protect them from the huge reptiles and dinosaurs under the protection of the Elder God Set. Set manifested on Earth and worked his will through all the ancient reptiles on Earth; they began exterminating the mammals, but Gaea called upon Atum to slay Set and drive him from Earth. This centuries long battle contributed to the extinction of the dinosaurs (except, of course, in the Savage Land and some other places). Eventually, there were not enough dinosaurs and huge reptiles on Earth to sustain Set and he was driven into another dimension unable to return to Earth.

(Conan: The Ravagers Out of Time - BTS) - Circa 18,500 BC, during the Pre-Cataclysmic Age, Kull and a time-displaced Conan and Red Sonja battle Rotath. The Pictish shaman Gonar invokes the names of numerous gods, demons and wizards to destroy Rotath, including the god Ra.

(Thor Annual#10 (fb) ) - Over thousands of years, from the Pre-Cataclysmic Age to the Hyborian Age to the Bronze Age (see comments) Gaea gave birth to new races of immortals that became the new gods of evolving human beings on the planet.

(Strange Tales I#70/5 (fb) - BTS) - Atum the creator who rose from the waters of Chaos, has decreed to Ptah the duty to protect the Pharaoh's who obey Atum's laws.

(All-New Official Handbook of the Marvel Universe Update#3) - Atum became Ammon Ra the Egyptian sun god. He ruled over the Ogdoad, the first incarnation of the Egyptian gods, but eventually they perished. Ammon Ra started anew with the Ennead and was succeeded as their ruler by his child Shu.

(Thor I#300 (fb) ) - Circa 100 0 AD Ammon Ra participated in a meeting of the Council of Godheads.

(Thor Annual#10) - When several of the gods of the dead lost their worshippers, they decided to merge their realms in order to acquire new souls into their realms. Their ritual actually opened a portal back to Atum and he returned to Earth as Demogorge. Sensing the evil energies generated by the seven gods of the dead, he commenced with absorbing them, but was fought back with representatives from the other gods of Earth. When he tried to absorb Thor, the thunder-god caused a shift in Demogorge’s palate and he expunged both the hero-gods and the death gods before transforming back into Atum and returning to his home dimension.

(Hulk vs. Hercules: When Titans Collide#1 (fb)) - When the Titan Cronus escaped from Tartarus Demogorge flew over Olympus, warning the gods that if Cronus bested them he would feast upon their realm. However, Cronus was defeated by Hercules and Demogorge departed.

(Thor Annual#14) - Thor called upon Atum for help to defeat Set who had been called back to Earth by the Deviant Lord Ghaur. Atum refused because he knew it would involve transforming into Demogorge. Thor forced him to become Demogorge once more and was consumed by the entity as a result of Atum’s wrath.  Thor managed to possess Demogorge, asserting his will as the dominant one, long enough to defeat Set, and Atum ended up releasing Thor from his body after realizing the passion and nobility in his efforts.

(Incredible Hercules#117 (fb)) - Horus recruited Atum/Demogorge to join the "God Squad" to oppose the Skrull gods.

(Incredible Hercules#117) - Demogorge appeared at a meeting of the Council of Godheads and joined the God Squad, departing in a ship through the Dreamtime to reach the realm of the Skrull gods.

(Incredible Hercules#118) - With the Godsquad, Demogorge stopped at the realm of Nightmare to ask for directions. They were each tormented by Nightmare until Mikaboshi freed them, at which point they fled.

(Incredible Hercules#119) - The Godsquad arrived in Skrull dreamtime, and they were assaulted by Gods conquered by Skrulls. Kirby/Kerberos, the coyote pup of Amadeus Cho, was revealed to be a Skrull imposter, and Demogorge consumed it. After Snowbird fought off the Skrulls' god agents, Demogorge and the others were confronted by Kly'bn & Sl'gur't. 

(Incredible Hercules#120) - Demogorge devoured Sl'gur't only to be torn apart from within as Sl'gur't proved to contain the essences of too many Godheads for him. Demogorge spine was subsequently used by Snowbird to skewer and apparently kill Kly'bn.

(Journey Into Mystery I#627 (fb)) - Demogorge attended the Devil's Advocacy to talk about the Serpent (Cul)'s actions on Earth.

Comments : Created by Alan Zelenetz and Robert Hall

Alan Zelentz probably chose the name "Atum" since in real-life history, the name comes from Egyptian culture, and the Egyptian pantheon represents one of the oldest of the pantheons of human civilization. (The Sumerian pantheon is also comparably old.) However, in the Marvel Universe, the Egyptian pantheon may not be among the oldest pantheons, since the history of the Marvel Universe includes two periods of relatively advanced civilization that predated ancient Egypt-the Pre-Cataclysmic Era and the Hyborian Era. You can read about the Pre-Cataclysmic gods under the comments to Varnae's entry and see a refresher on the Hyborian Era gods here. (In addition, Red Sonja III#4 indicated that a race of "titans" predated the "gods of Lemuria" and "the lords of Atlantis", with two of these "titans", Byrina and Calanda, named.)

It is conceivable, however, unrevealed if Atum is the same as Atum-Re (the Egyptian counterpart to the Olympian Ouranos).

Actually, Atum’s relationship to Demogorge is rather similar to that between Dr. Bruce Banner and the Hulk.

A caveat vis a vis the way the gods are depicted in flashbacks to the Demiurge; Silver Surfer Annual#2/7, Doctor Strange III#11/2, and Set's Update '89#7 entry noted that the Elder Gods did not have forms that human eyes could perceive, and it is only for the sake of convenience that they are shown as humanoid, or in Set's case, reptillian.
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Y'Garon (or his brothers) and Belathauzer have never been shown or mentioned by name in any of the retellings of the Demogorge/Atum/Demiurge story. They were designated as one of the Elder Gods that fled from Atum in the Demons entry in The Official Handbook of the Marvel Universe Deluxe Edition#3 and this has been repeated in other sources, such as the Marvel Age Midnight Sons Special.

Following off of an idea from Doctor Strange III#8, Doctor Strange Annual#2 (published around 1991) had Rintrah go through a list of Doctor Strange's worst opponents, and note that a great concentration of evil energy was left around after the Demogorge's battle with the Elder Gods. In time, this energy split, producing Thog, Satannish (later revealed as a creation of Dormammu), Mephisto, and other, newer demons.

The story in Iron Man Annual#10 indicates that Gaea allowed the dinosaurs to become extinct because she did not think they could have evolved into sentient lifeforms. In fact, several alternate Earths (or their natives) have been seen that are populated by sentient races descended from the dinosaurs: Earth-99476 (Excalibur I#9-10, #51); Cretacious Sam from Nightcrawler I#4, Dino-Knight from Moon Knight III#42, Dinosaur World from Devil Dinosaur#1 and Marvel Two-In-One#73, Kang-Mesozoic from Avengers I#296, a throwaway world in Thor I#440, and a world seen in a story reprinted in Fantasy Masterpieces#1. Gaea may have jumped the gun.

At some point Chthon bound some of Demogorge's power into a Darkhold page. The page was first seen in Darkhold#8, where it was given to Samantha Regent by the Dwarf. It was in her possession in Nightstalkers#8-9 until it was stolen from her. Blade retrieved it from the thie in Nightstalkers#10 and used it in a plan to destroy all magic. It turned him into Switchblade and Blade had to be stopped by the Darkhold Redeemers. The storyline named Midnight Massacre ran through Nightstalkers#10, Ghost Rider III#40, Darkhold#11, Morbius#12 and Spirits of Vengeance#13.
--Markus Raymond

Demogorge received an entry in the All-New OHotMU Update#3.

CLARIFICATIONS:

Demogorge is not to be confused with Demiurge (Thor Annual#10)

Damballah, the spawn of Set, should not be confused with:

• Dam-Ayido, also called Damballah, the African god who presumably stole his worshippers, @ Dracula Lives#2/7

Set, the Elder God, should not be confused with:

• Seth, the Egyptian god who stole his worshippers, @ Thor I#240
  
• Apocalypse, whom the ancient Egyptians confused with both Set and Seth, @ X-Factor I#5