In Greek mythology, Theia (ˈθiːə; Theía, also rendered Thea or Thia), also called Euryphaessa (Εὐρυφάεσσα) "wide-shining", is one of the twelve Titans, the children of the earth goddess Gaia and the sky god Uranus. She is the Greek goddess of sight and vision, and by extension the goddess who endowed gold, silver and gems with their brilliance and intrinsic value. Her brother-consort is Hyperion, a Titan and god of the sun, and together they are the parents of Helios (the Sun), Selene (the Moon), and Eos (the Dawn). She seems to be the same with Aethra, the consort of Hyperion and mother of his children in some accounts. Like her husband, Theia features scarcely in myth, being mostly important for the children she bore, though she appears in some texts and rare traditions.
The name Theia alone means simply "goddess" or "divine"; Theia Euryphaessa (Θεία Εὐρυφάεσσα) brings overtones of extent (εὐρύς, eurys, "wide", root: εὐρυ-/εὐρε-) and brightness (φάος, phaos, "light", root: φαεσ-).
The usual accounts gave her an equally primal origin, said to be the eldest daughter of Gaia (Earth) and Uranus (Sky). She is thus the sister of the Titans (Oceanus, Crius, Hyperion, Iapetus, Coeus, Themis, Rhea, Phoebe, Tethys, Mnemosyne, Cronus and sometimes Dione), the Cyclopes, the Hecatoncheires, the Giants, the Meliae, the Erinyes, and the half-sister of Aphrodite (in some versions), Typhon, Python, Pontus, Thaumas, Phorcys, Nereus, Eurybia and Ceto. By her brother-husband Hyperion she is the mother of Helios, Selene and Eos. Robert Graves also relates that later Theia is referred to as the cow-eyed Euryphaessa who gave birth to Helios in myths dating to classical antiquity.
Once paired in later myths with her Titan brother Hyperion as her husband, "mild-eyed Euryphaessa, the far-shining one" of the Homeric Hymn to Helios, was said to be the mother of Helios (the Sun), Selene (the Moon), and Eos (the Dawn). Gaius Valerius Catullus described those three lights of the heavens as "Theia's illustrious progeny" in the sixty-sixth of his carmina.