Chthonic (from Greek χθόνιος — chthonios, “in, under, or beneath the earth”, from χθών — chthōn “earth”; pertaining to the Earth; earthy; subterranean) designates, or pertains to, deities or spirits of the underworld, especially in relation to Greek religion.

Greek khthon is one of several words for “earth”; it typically refers to the interior of the soil, rather than the living surface of the land (as Gaia or Ge does) or the land as territory (as khora (χώρα) does). It evokes both ”abundance” and “the grave”.