The Protogenoi, also known as the primordial gods, are the first race of immortals to come into existence, the majority of whom were born directly from the void of Chaos. Unlike the Titans and the gods, the Protogenoi are essentially sentient aspects of the universe itself, and therefore, they cannot truly be killed. Even the power of Kronos's scythe and other weapons of immense power is ultimately only able to disperse their physical forms.

The beginning

Chaos, the first Protogenos

Protogenoi can also manifest in physical form as seen with Gaea, Ouranos, Tartarus and Nyx. They can be banished from manifesting in the world physically but their consciousness can never be destroyed. They have absolute and total control over a particular aspect of the entire universe which makes them immensely powerful and difficult to kill in their physical form.


Birth of the Protogenoi

Initially, all the matter in the cosmos drifted around in a gloomy, soupy mist called Chaos. It was the first of the Protogenoi, and eventually some of its matter collected to form the earth, which developed a personality that called herself Gaea. After a period of time, the sky appeared: a great dome above the earth that became Ouranos. He married Gaea, but more Protogenoi followed in suit such as Tartarus and Pontus.


Ouranos casting his children into Tartarus

Water pooled out of the mist of Chaos and formed the first seas on earth, that like his predecessors, developed a consciousness: Pontus. Finally, another dome emerged from Chaos. Unlike Ouranos, however, this was Tartarus, the Pit of Evil right beneath the earth itself. Both of them harbored feelings for Gaea, which made her relationship with Ouranos rather difficult.

Other Protogenoi also appeared, namely Nyx, daughter of Chaos and Tartarus, as well as Protogenos of Night. Without the aid of a consort, she gave birth to Hemera, who ironically became the Protogenos of Day.

First Titan War

Although Gaea originally wanted the Olympians to win in this war, she became unhappy with the way the Olympians ruled and with Tartarus, gave birth to another brood of children, The Gigantes each one of them born to oppose a certain god. As the giants could only be killed by the combined power of a god and a demigod, the gods called upon Hercules and Dionysus, two of the most powerful demigods ever to help them defeat the giants. Gaea then gave birth to Typhon whom Zeus defeated with the help of several other gods using trickery. With the last child of hers defeated, Gaea admitted defeat and fell back to her slumber.

Second Giant War

Following the end of the Second Olympian War, Gaea stirred from her slumber and began raising the Gigantes from Tartarus to oppose the Olympian gods. Not only did several deceased beings return to life, but other Protogenoi such as Tartarus and Nyx actively began to participate in the war.

The Argo II was attacked by the Ourae when it tried to cross the Apennine Mountains, as they are children of Gaea.

After falling into Tartarus, Percy Jackson and Annabeth Chase encountered Akhlys, Nyx, and finally the embodiment of Tartarus himself. Through the combined efforts of Iapetus and Damasen fighting him off, Percy and Annabeth managed to escape from Tartarus.

At the end of the war, Gaea was dispersed so thin that hopefully she would not be able to form a consciousness again, as had happened to Kronos.


Gaea, a protengos


As they are the very components that make up the universe, they have complete control of the domain they represent, which can rival or even exceed that of gods who preside over them. In addition, all the Protogenoi wield immeasurable power, rendering them the most powerful beings in Greek mythology.

All Protogenoi appear to be capable of manifesting in physical form to interact with lesser beings. Ouranos was able to appear in the form of a "tall, buff guy with longish hair", but still retained physical traits native to his domain, such as his skin being "blue with cloudy patterns" during the day and "dark with glimmering stars" during the night.

As the sentient aspects of the Universe itself, all Protogenoi are incapable of truly dying. Even if they were to be scattered and their physical form permanently destroyed, they would remain both alive and immortal.


Despite their great power, Protogenoi are still susceptible to being weakened to the point of dormancy. This is shown when Ouranos was ambushed by his sons and had his physical body cut to pieces by Kronos with the scythe. After the murder, Ouranos' essence was scattered and his physical form permanently destroyed, but he remains alive and immortal nonetheless.

Furthermore, if separated from their domain, Protogenoi are relatively less powerful than they would be if they were in their element. This was exploited both by the Titans in killing of Ouranos and by Jason Grace when he used his aerokinetic powers to sever Gaea's contact with the earth, ultimately leading to her defeat when she was blown up by Leo Valdez fire supernova and a missile.

Some Protogenoi don't have a totally physical or even physical domain, such as Nyx, Erebus, Hemera, Aither, Chronos and Ananke alongside some others. This could mean that they are more weak than the others, and also more easy to "scatter."

Nyx, Erebus, Hemera & Aither are stronger in their domain (physical or not) and weaker in their opposite domains, respectively.

The Protogenoi

  • Chaos: Protogenos of the Void and Creation
  • Gaea: Protogenos of the Earth and Nature
  • Ouranos: Protogenos of the Sky and Heavens
  • Pontos: Protogenos of the Sea
  • Tartarus: Protogenos of the Pit
  • Nyx: Protogenos of Night
  • Erebus: Protogenos of Darkness and Mist
  • Hemera: Protogenos of Day
  • Aither: Protogenos of Upper Air and Light
  • Akhlys: Protogenos of Misery and Poison
  • Ourae: Protogenoi of Mountains
  • Elpis: Protogenos of Hope
  • Thalassa: Protogenos of the Sea
  • Chronos-Aeon: Protogenos of Time and Eternity
  • Ananke: Protogenos of Inevitability and Fate
  • Nesoi: Protogenoi of Islands
  • Physis: Protogenos of Nature
  • Hydros: Protogenos of Fresh Water and Mud
  • Phanes: Protogenos of Procreation and Generation of New Life



  • Gaea is the only Protogenos to be in all five books of The Heroes of Olympus series.
  • The majority of the first Protogenoi (excluding Gaea and Pontos) make an appearance in The House of Hades as antagonists. They are the Ourea, Akhlys, Nyx, and Tartarus.
  • One of the most powerful demonstration of the protogenoi power is that Nyx is able to subject half of the Earth with darkness and Hemera the other with light, with the both without tiring
    • Curiously all of the Big Three have a protogenoi counterpart, Hades being Tartarus, Poseidon being Pontos and Zeus being Ouranos.
      • Interestingly the order of their counterpart born is the totally contrary to them, being: Ouranos, Pontos and Tartarus.
      • Although Demeter has also a counterpart, who would be Gaea, the Mother Earth. Also, Demeter's name is implied to mean "Earth-Mother".