In ancient Greek religion and myth, Demeter is the goddess of the harvest, who presided over grains and the fertility of the earth. Her cult titles include Sito (Σιτώ), "she of the Grain", as the giver of food or grain and Thesmophoros (θεσμός, thesmos: divine order, unwritten law; "phoros": bringer, bearer), "Law-Bringer," as a mark of the civilized existence of agricultural society.

Though Demeter is often described simply as the goddess of the harvest, she presided also over the sacred law, and the cycle of life and death. She and her daughter Persephone were the central figures of the Eleusinian Mysteries that predated the Olympian pantheon. In the Linear B Mycenean Greek tablets of circa 1400–1200 BC found at Pylos, the "two mistresses and the king" may be related with Demeter, Persephone and Poseidon. Her Roman equivalent is Ceres.