The daughter of Uranus and Gaia, Thea was one of the first twelve Titans in Greek mythology. Wither her lover and brother Hyperion, Thea had the sun good Helios, the moon goddess Selene, and the dawn goddess Eos. Thea fought alongside her fellow Titans in the cataclysmic conflict known as the Titanomachy; when they ultimately lost the conflict, however, she was condemned to the dismal realm of Tartarus.
The name “Thea,” alternatively spelled Theia, simply meant “goddess” and was derived from the ancient Greek word theos. This ancient Greek word is also the root of modern English terms such as “theism” and “theology.”
Thea was sometimes referred to as Euryphaessa, meaning “wide-shining” or “all-bright.”
Thea’s most common epithet, Euryphaessa (the “wide-shining”), suggests that she had an association with heavenly bodies and others forms of light; such an association was further supported by her motherhood of Helios (sun), Selene (moon), and Eos (dawn). How this relationship shaped her other attributes remains unclear.
The daughter of primordial deities Gaia, who embodied mother earth, and Uranus, who personified the heavens above, Thea was one of twelve children known as the Titans. Among her brothers and sisters were the other Titans—Coeus, Crius, Cronus, Hyperion, Iapetus, Oceanus, Mnemosyne, Phoebe, Tethys, Thea, Themis, and Rhea—as well as the Hecatoncheires and the Cyclopes, baneful monsters who terrorized gods and mortals alike.
In her womanhood, Thea took her brother Hyperion as her lover. They had three children, each associated with the light of a celestial body: Helios, the incarnatation of the sun; Selene, who embodied the moon and gave off pale light; and Eos, the dawn, whose light preceded Helios every morning.
Thea appeared in many sources of Greek mythology thanks to her position as mother of the sun god Helios, and, to a lesser extent, mother of Selene and Eos. As Hesiod wrote in the eighth century BCE:
And Theia was subject in love to Hyperion and bare great Helius (Sun) and clear Selene (Moon) and Eos (Dawn) who shines upon all that are on earth and upon the deathless Gods who live in the wide heaven.1
The seventh century BCE Homeric Hymn to Helios similarly praised the sun god’s mother, here referred to as Euryphaessa:
And now, O Muse Calliope, daughter of Zeus, begin to sing of glowing Helios whom mild-eyed Euryphaessa, the far-shining one, bare to the Son of Earth and starry Heaven. For Hyperion wedded glorious Euryphaessa, his own sister, who bare him lovely children, rosy-armed Eos and rich-tressed Selene and tireless Helios who is like the deathless gods.2
The lyric poet Pindar further praised the sun’s “bright” and “shining” mother in the fifth of his Isthmian odes, written in the fifth century BCE:
Mother of the Sun, Theia of many names, for your sake men honor gold as more powerful than anything else;  and through the value you bestow on them, o queen, ships contending on the sea and yoked teams of horses in swift-whirling contests become marvels.3
Not commonly depicted in popular culture, Thea appeared in the seventh episode of Xena: Warrior Princess, where she was awakened from a centuries-long slumber alongside Crius and Hyperion.
Anonymous. Homeric Hymn to Helios. Translated by Hugh Evelyn-White. Perseus Digital Library, Tufts University. Accessed on February 20, 2020. https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0138%3Ahymn%3D31.
Hesiod. Theogony. Translated by Hugh Evelyn-White. Internet Sacred Text Archive. Accessed February 19, 2020. https://www.sacred-texts.com/cla/hesiod/theogony.htm.
Pindar. Isthmian Odes. Translated by Diane Arnson Svarlien. Perseus Digital Library, Tufts University. Accessed on February 20, 2020. http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0162%3Abook%3DI.%3Apoem%3D5.
“Theia.” Wikipedia. Accessed on February 19, 2020. https://en.wikipedia.org/wiki/Theia.
Hesiod, Theogony, translated by Hugh Evelyn-White, 371-374. https://www.sacred-texts.com/cla/hesiod/theogony.htm. ↩
Homeric Hymn to Helios, translated by Hugh Evelyn-White. https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0138%3Ahymn%3D31. ↩
Pindar, Isthmian Odes, Fifth Isthmian Ode, translated by Diane Arnson Svarlien. http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0162%3Abook%3DI.%3Apoem%3D5. ↩