According to Greek mythology, Ion (//; Greek: Ἴων, gen.: Ἴωνος) was the illegitimate child of Creüsa, daughter of Erechtheus and wife of Xuthus. Creusa conceived Ion with Apollo then she abandoned the child. Apollo asked Hermes to take Ion from his cradle. Ion was saved (and raised) by a priestess of the Delphic Oracle. Later, Xuthus was informed by the oracle that the first person he met when leaving the oracle would be his son, and this person was Ion. He interpreted it to mean that he had fathered Ion, when, in fact, Apollo was giving him Ion as an adoptive son. Creusa was planning on killing Ion due to her jealousy that Xuthus had a son while she was still childless. At the same time, Ion was planning on doing harm to Creusa. In the end, Creusa found out that Ion was her child, and only Xuthus' adopted child. This is the story told in the tragedy Ion by Euripides.
In the other accounts, Ion was the founder of Helike (the modern Eliki) in Achaea. Ion was the son of Xuthus (rather than Apollo) who was brought to the area during the reign of king Selinus. He married the girl named Helike who succeeded the throne. He built the city of Eliki after the name of his wife, and made it the capital of the kingdom. Later he took an expedition against Eleusis (now Elefsina) with the help of the Athenian and in the battle he was killed near Eleusis.
Ion was also believed to have founded a primary tribe of Greece, the Ionians. He has often been identified with the Javan mentioned in the Hebrew Bible. The earlier Greek form of the name was *Ἰάϝων "Iáwōn", which, with the loss of the digamma, later became Ἰάων Iáōn, or plural Iáōnes, as seen in epic poetry. In addition, Dionysius Periegetes ver. 416 mentions a river in Arcadia called Iaon. This river Iaon is further alluded to in Hesiod's Hymns of Callimachus, Hymn to Jupiter 22. This river has also been connected to the earlier forms of the name.
- Yona – covers other names for the Greeks derived from Ion and the Ionians, found from the Near East to India
- Hesiod, Catalogue of Women fr. 10(a).
- Bromiley, Geoffrey William (General Editor) (1994). The International Standard Bible Encyclopedia: Volume Two: Fully Revised: E-J: Javan. Grand Rapids, Michigan: Wm. B. Eerdmans Publishing. pp. 971. ISBN 0-8028-3782-4.
- Woodhouse’s English-Greek Dictionary, 1910, p. 1014
- Hesiod, Catalogue of Women fr. 10(a).23. ("Ἰάονά τε κλυ]τόπωλ[ο]ν")
- Iliad, 13.685 ("Ἔνθα δὲ Βοιωτοὶ καὶ Ἰάονες ἑλκεχίτωνες"), mentioned in Israel and Hellas (1995) by John Pairman Brown, p. 82.
- The Early Ionians by George Huxley (1966), p. 166.