The Theogony is a large synthesis of the wider local Greek traditions concerning the Gods origins, organized as a narrative.
Note:This is a brief summary
The poem starts with a blessing from the Muses and thanks them for inspiration
Cosmogony and Castration of Uranus
Chaos was the first to come to be, followed by Gaia, Tartarus and Eros. From Chaos came forth Erebos and Nyx, and from Night and Erebos came Aither and Hemera. From Earth came Ouranus, The Ourea and Pontos.
Gaia then lay with Ouranus and bore Oceanos, Koios, Krios, Hyperion, Iapetos, Theia, Rhea, Themis, Mnemosyne, Phoebe and Tethys. After them Kronus was born. After that she mated with Ouranus once again, and bare the Kyklopes; Brontes, Steropes and Arges, who made thunder for Zeus. She also had the Hekatonchires; Kottos, Briareos, and Gyges. Ouranus was disgusted with them and hide them away in Gaia. She asked the Titans to punish their father, and Kronos volunteered, and castrated him with the sickle his mother gave him. From the drops of blood which fell on Earth, the Erinyes and the Gigantes, the Nymphs Meliai all around Earth. From the sea foam came Aphrodite, and with her came Eros and Himeros.
Spirits of Night
Nyx bare hateful Moros (Doom) and Ker (Fate) and Thanatos (Death), and Hypnos (Sleep) and the tribe of Oneiroi (Dreams). And she lay with none, bare Momos (Criticism) and Oizys (Misery), and the Hesperides. Also she bare the Moirai (Fates) and the ruthless Keres (Deaths). Also she bare Nemesis to afflict mortal men, and Apate (Deceit) and Philotes (Sex) and Geras (Old Age) and Eris (Strife)."
And Eris bore Ponos (Toil), and Lethe (Forgetfulness), and Limos (Starvation), and the Algea (Pains), the Hysminai (Fightings) and the Makhai (Battles), the Phonoi (Murders) and the Androktasiai (Man-slaughters), the Neikea (Quarrels), the Pseudo-Logoi (Lies), the Amphilogiai (Disputes), and Dysnomia (Lawlessness) and Ate (Ruin) and Horkos (Oath).
Pontos and Gaia had Nereus, the old man of the sea, Thaumas and Phorkys, Keto and Eurybia. And Nereus and Doris, daughter of Okeanus, had the Nereides, who included Amphrite and Galene and the other 48 daughters.
Keto and Phorkys bare the Graiai and the Gorgons; Sthenno, Eurayle and Medusa, she was mortal, but the other two were not, she lay with Posiedon and when she was beheaded by Persues, Khrysaor and Pegasus sprang out. Pegasus went to the gods and brings Zeus thunder and lightning.
And in a cave she bare another monster, Ekhinda, who is half nymph and half snake. Typhoeus was joined in love to her. So she conceived Orthus, hound of Geryon, and Cerberus, the hound of Hades. And the Hydra and Herakles, son of Zeus, together with Iolaus, destroyed her. She was the mother of Khimaira who breathed fire. Pegasus and Bellerophon slayed her. But Khimaira was in love with Orthus and brought the deadly Sphinx which destroyed the Cadmeans and the Nemean Lion which Hera brought up and made to haunt the hills of Nemea. There he preyed upon tribes and had power over Tretus of Nemea and Apesas, yet Herakles overcame him.
And Keto bore to Phorkys her youngest, Ladon, the Hesperides Dragon.
And Styx, daughter of Okeanus was joined to Pallas and bare Zelus and Nike, Kratos and Bia, who live in Zeus's house. Zeus called all the immortal's to Olympus and said that those who would help him fight against the Titans he would have their office they had before. And Styx came to Olympus and Zeus honoured her and appointed her to be the oath of the gods.
Hymn to Hekate, Children of Kronus
And she bare Hekate, whom Zeus honoured above all.
But Rhea was subject in love to Kronos and bare children Hestia, Demeter, Hera and Hades, Poseidon and Zeus. These Kronos swallowed as each came out, as he learned from Gaia and Ouranus that he would be overthrown by his son. So when Rhea was pregnant with Zeus, she consulted with her parents, so they sent her to Lyetus and to Crete and when she gave birth, Earth carried him to Lyctus at night, then to a remote cave beneath Mount Aegeum. Rhea gave Kronos a stone wrapped in cloth. Then he took it and swallowed it. After years Kronos vomited it out and Zeus set it in the Earth at Pytho under the glens of Parnassus and he set free the Kyklopes and the Hekatonkheires and they were grateful and gave him thunder and lightning, for before, they were hidden in Earth.