Uranus

Uranus was a primal Greek god, symbolising the sky. According to Hesiod's Theogony, he was born by Gaea alone. Other sources say that his parents were Gaea and Chaos, or Gaea and Aether.
Uranus and Gaea had many children; the twelve Titans, three Cyclopes, and three Hecatoncheires. Hating his children, Uranus banished them to Tartarus, inside Gaea. Gaea was infuriated and created a diamond sickle, which she gave to Cronus, one of the Titans. Cronus found his father and castrated him in his sleep; from the blood that fell on the earth, the Erinnyes, the Giants and the Meliads were born; while from the sperm that fell into the sea, Aphrodite was born. Thus ended the reign of Uranus, and Cronus became the new ruler of the universe.
See Also: Gaea, Titans, The Creation, Cronus
Uranus Is also called Caelus, Ouranos.
Gaea

Gaea was a primal Greek goddess, one of the deities that governed the universe before the Titans. She symbolised the Earth, and was the mother of everything.
According to one version, Gaea, along with Chaos and Eros, coexisted during the creation of the world. Another version has it that the three of them were born out of the Cosmic Egg, which itself was created out of nothingness. Hesiod then tells us that from the union of Gaea and Chaos - and supported by Eros - Uranus was born. Gaea and Uranus gave birth to the Giants, the Titans, Oceanus and the whole world. At that point, Uranus decided to stop Gaea from creating anything else and sent his children inside her; Gaea was infuriated and allied with one of her Titan sons, Cronus, managing to overthrow Uranus. However, due to the cruelty of Cronus and his determination to remain on the throne, Gaea assisted Zeus in overthrowing Cronus, which marked the end of the age of the Titans.
See Also: Titans, Uranus, Cronus, Zeus, The Creation
Gaea Is also called Terra, Gaia, Gi, Ge.
Thanatos

Thanatos was the daemonic representation of death in Ancient Greek mythology (daemonic here is used with its classical meaning, which refers to benevolent or benign nature spirits). He did not play a major part in Greek mythology and rarely appeared in any stories, as he was mostly displaced by Hades, the god of the Underworld.
He was the son of Nyx (the Night) and Erebos (the Darkness), while his twin brother was Hypnos (the Sleep). Other siblings of Thanatos and Hypnos included Geras (old age), Eris (strife), Nemesis (retribution), Apate (deception) and Charon (the boatman that led the souls to the Underworld).
Thanatos was believed to be merciless and indiscriminate, and both mortals and gods hated him. However, he could sometimes be outsmarted. In a myth, Thanatos was told by Zeus to chain King Sisyphus in the Underworld, as it was time for him to die. Sisyphus managed to chain Thanatos in his own fetters, thus protecting all mortals from dying while the god was chained. In the end, god Ares, angry that at the wars he waged noone died, freed Thanatos and gave Sisyphus to him.
See Also: Hades, Nyx, Erebos, Hypnos, Eris, Nemesis
Thanatos Is also called Thanatus, Mors, Letus, Letum.
Nyx

Nyx was a primordial deity in Greek mythology that preceded the Titans and the Olympians, and was the personification of the night. She was the daughter of Chaos, out of which all creation originated, and the sister of Erebus, Gaea and Tartarus. She was married to Erebus and had a number of children, including Nemesis (retribution), Hypnos (sleep), Thanatos (death), Geras (old age), Eris (strife) and Charon (the boatman who brought the souls of the dead to the gates of the underworld). According to Hesiod, Nyx's home was in Tartarus, along with her children Hypnos and Thanatos.
See Also: Chaos, Erebus, Gaea, Tartarus
Nyx Is also called Nox.
Europa

Europa was initially a Cretan moon goddess, who was incorporated into the Greek mythology as a virgin Phoenician princess. She was the daughter of the King Agenor of Sidon and Europe was named after her.
She had an affair with Zeus, which Hera never learned about and therefore, never tried to pursue Europa to punish her. One night, Europa dreamed of two continents, which had taken the forms of women, arguing over her. Asia maintained that since Europa had been born in Asia, she belonged to her. The other continent, which was nameless, said that her birth was not important and that Zeus would give Europa to her. Disturbed by the dream, Europa woke up in the early hours and did not go back to sleep. She summoned her companions, who were all daughters of nobility and of her age. It was a beautiful day and they went off gathering flowers by the sea. Zeus noticed this charming group, particularly Europa, who was the prettiest of the maidens. According to some sources, Eros induced him into action with one of his arrows, although Zeus never really needed much persuasion. In any case, Zeus appeared to the group in the form of a white bull, one that was more beautiful than any other; a bull that smelled of flowers and lowed beautifully; a bull so obviously gentle that all the maidens rushed to stroke and pet it. The bull laid down in front of Europa and she slid onto its back. Instantly, the bull charged off, plunging into the sea, and began to swim rapidly from the shore. Europa saw that a procession had joined them, Nereids riding dolphins, Triton blowing his horn, even Poseidon. From this, she realized that the bull must be a god and she pleaded to pity her. Zeus spoke to her and explained his love. He took her to Crete, where he had been raised, and promised her that she would bear him many famous sons. Her sons included Minos and Rhadamanthus.
See Also: Zeus, Hera, Minos, Rhadamanthus