The Protogenoi (Πρωτογενοι) are the First Born Deities of the Hellenic Kosmos. They are the building blocks of the universe, primordial Deities. I have written before about Them, in a post about genealogy of the Gods.

The Protogenoi we know of are: Aether (Αἰθήρ, 'Light'), Ananke (Ἀνάγκη, 'Fate' or 'Compulsion'), Khronos (Χρόνος, 'Time'), Erebos (Ἔρεβος, 'Darkness'), Eros (Ἔρως, 'Desire' or 'Love'), Gaea (Γαῖα, 'Earth'), Hemera (Ἡμέρα, 'Day'), Hydros (Ὑδρος, 'Primordial Waters'), Khaos (χάος, 'Chaos' or 'Air'), Nêsoi (Νησοι, 'Islands'), Nyx (Νύξ, 'Night'), Ôkeanos (Ωκεανος, 'Water'), Ourea (Oὔρεα, 'Mountains'), Phanes (Φάνης 'Procreation'), Pontos (Πόντος, 'Sea'), Phusis (φύσις, 'Nature'), Tartaros (Τάρταρος), Thalassa (Θάλασσα, 'Sea'), Thesis (Θεσις, 'Creation'), Uranos (Οὐρανός, 'Sky').

As might have become apparently from the, previously mentioned, earlier published post; any mythology from this era is incredibly mucky. There are a few sources we can track the beginning of the universe to; because that is where the Protogenoi were born in--or from; the beginning of the universe. They are the embodiments of the aspects of life They are named after. Zeus may be Lord of the Sky, but the sky itself is a primordial Deity, distant from humanity but ever-present.

Hesiod, in his 'Theogony', writes:

"Verily at the first Chaos came to be, but next wide-bosomed Earth, the ever-sure foundations of all the deathless ones who hold the peaks of snowy Olympus, and dim Tartarus in the depth of the wide-pathed Earth, and Eros, fairest among the deathless gods, who unnerves the limbs and overcomes the mind and wise counsels of all gods and all men within them. From Chaos came forth Erebus and black Night; but of Night were born Aether and Day, whom she conceived and bare from union in love with Erebus. And Earth first bare starry Heaven, equal to herself, to cover her on every side, and to be an ever-sure abiding-place for the blessed gods. And she brought forth long Hills, graceful haunts of the goddess-Nymphs who dwell amongst the glens of the hills. She bare also the fruitless deep with his raging swell, Pontus, without sweet union of love."

And then there is another version out there, articulated best by playwright Aristophanes in 'The Birds':

"At the start, there was Chaos, and Night, and pitch-black Erebus, and spacious Tartarus. There was no earth, no heaven, no atmosphere. Then in the wide womb of Erebus, that boundless space, black-winged Night, first creature born, made pregnant by the wind, once laid an egg. 
It hatched, when seasons came around, and out of it sprang Love—the source of all desire, on his back the glitter of his golden wings, just like the swirling whirlwind. In broad Tartarus, Love had sex with murky Chaos. From them our race was born—our first glimpse of the light.
         Before that there was no immortal race at all, not before Love mixed all things up. But once they’d bred and blended in with one another, Heaven was born, Ocean and Earth—and all that clan of deathless Gods."

Within Hellenismos, the Protogenoi are not often mentioned or worshipped. Eros and Gaea may receive honorable mention on occasion but the Olympians have much more sway. The Protogenoi are specialists, beings of one base component of life. They hold sway over these and, when roused, They wield terrible power, without regard of those who are in the way, be they Gods, Demi-Gods or mortals. The Olympians are (besides Hermes) moral Deities; They wield Their power thoughtfully. The Protogenoi are too ancient, too huge, to hold back Their power and take into account our little race of mortals. I suspect that therefor the Protogenoi are appeased more often than worshipped, if thought of at all in a ritual setting. 

I'm fascinated with the Protogenoi. If I ever founded (or revived? Were there cults for the Protogenoi?) a Mystery Cult, it would be for the Protogenoi. I won't do this without considerable research, however, and on most days I doubt I would have the courage to do so anyway.

The true nature of the Protogenoi is shrouded by time. Much of their mysteries were lost. Yet, they, too, are part of the Hellenic pantheon. They, too, hold sway over the universe. Deities like this should not be forgotten, and they should most certainly never be ignored.