Gaia and Uranus gave birth to the race of Titans, who warred unsuccessfully against the Olympians in the great Titanomachy, which lasted ten years. The meaning of "Titan," in spite of many suggestions, remains unclear. In general, the Titans symbolized the powerful forces of nature, untamed by the rational and patriarchal rule of the Olympians. They were seldom represented in art and garnered little worship. Two notable Titans were the watery male Oceanus and the female Tethys, probably derived from the Babylonian watery Tiamat.Oceanus was a river that surrounded the world. According to Homer, Oceanus and Tethys gave birth to all the other gods. Oceanus also fed all the waters in wells, fountains, and rivers. From Oceanus and Tethys came the three thousand Oceanids, spirits of the sea, rivers, and springs.
Other Titans include Phoebe, who may be connected with the sky, and Themis, who represented that which is fixed and settled. She controlled the Delphic Oracle before it passed to Apollo and bore children to Zeus, as did the Titan Mnemosyne, "memory." Cronus and Rhea were parents or grandparents of the Twelve Olympians, including Zeus.
by Barry Powell, 30-Second Myths