In Greek mythology, Echion (Ancient Greek Ἐχίων, from ἔχις, "viper") is one of the five surviving Spartoi, the "sown men" who sprang from the dragon's teeth sown by Cadmus at Thebes. He married Cadmus' daughter Agave and fathered Pentheus, the doomed king of Thebes in Euripides' Bacchae. Tradition also credits him with helping Cadmus build Thebes and with founding the Malian city of Echinos.
Adapted from Wikipedia, "Echion" · CC BY-SA 4.0
I.The Spartoi
When Cadmus sowed the teeth of the Ismenian dragon, armed men sprang from the earth and fought among themselves. Five survivors — Echion, Chthonius, Hyperenor, Pelorus, and Udaeus — became the founding nobles of Cadmean Thebes. Scholia, Apollodorus, Hyginus, and Ovid preserve the episode with minor name variation.
Echion was remembered for valor in battle. For that bravery Cadmus preferred him as son-in-law: he married Agave and became father of Pentheus (and, in some notices, of Epeiros).
II.Thebes and later tradition
Pausanias and related sources place Echion among those who assisted Cadmus in building Thebes. He was said to have dedicated a temple of Cybele in Boeotia. Pseudo-Scymnus and Stephanus of Byzantium connect him with the foundation of Echinos in Malis, giving the city an eponymous Cadmean ancestor.
Through Agave and Pentheus he stands at the root of the Theban royal disaster dramatized in the Bacchae, when Dionysus destroys Pentheus for denying his cult.
III.Homonyms
This atlas entry (echion) is the Theban Spartos, husband of Agave. Distinct from Echion son of Hermes and Antianira (echion-hermes), the Argonaut from Alope; from a Giant of that name; from a Greek at Troy said to have died leaping from the Wooden Horse; and from a Dulichian suitor of Penelope (echion-dulichium).