Eumolpos (Greek Εὔμολπος, the beautiful singing ) is in Greek mythology an immigrant Thracian king in Eleusis, son of Poseidon and Chione, as a warrior, a priest of Demeter and singer awarded the same.
As Chione of Poseidon was pregnant she hid it from her father, gave birth Eumolpos secretly and threw him into the sea. Poseidon received him and took him to Ethiopia to his daughter Benthesikyme who raised him. He married a daughter of the King of Ethiopia. But since he transgressed against the sister of his wife he was banished. So he returned with his son Imma Rados (which is mentioned in the Libraries of Apollodorus Ismarus ) back to his native Thrace.
Imma Rados married a daughter of Tegyrios, king of Thrace. As to overthrow either Imma Rados or Eumolpos, there are different traditions, Tegyrios both were expelled from the country and came so to Eleusis. How Eumolpos came to the throne of Thrace is also told differently: either died Imma Rados and Eumolpos could return and received from Tegyrios the throne. or Tegyrios awarded Eumolpos on his deathbed and gave him dominion.
As kindled a war between the Eleusinians and Athens, Eumolpus made only mentioned help, but was slain by Imma Rados and the allies Phorbas of Erechtheus. According to another tradition, only his son Imma Rados, and Eumolpus fell even joined with the Athenians a comparison, alleging rule Erechtheus in Athens as king, Eumolpos but with the daughters of Celeus ( Diogeneia, Pammerope and Saisara ) should preside over the services of Demeter at Eleusis. Therefore the Eumolpus the introduction of the Eleusinian Mysteries was attributed and written records of the same under his name.
The succession of the priesthood is to Keryx, either a younger son of Eumolpus, or the Son of Aglauros who entered. Among the descendants of Eumolpus, the Eumolpidae, and the descendants of Keryx, the Keryken, the dignity of the Hierophant at Eleusis was hereditary.
After Alexandrian poets Eumolpos was also a teacher of Hercules in music and in the Mysteries. Heracles was particularly interested in the mysteries to go to Hades and bring from there the hell hound Cerberus. According to Hyginus Mythographus he won at the funeral games for Pelias in singing ( to the flute playing of Olympos ) the price.