In Greek mythology, Xuthus (/ˈz(j)uːθəs/; Ancient Greek: Ξοῦθος Xouthos) was a Phthian prince who later became a king of Peloponnesus. He was the founder (through his sons) of the Achaean and Ionian nations.

According to the author Robert Graves, Xuthus' name came from the ancient Greek word strouthos, meaning "sparrow".^[1]

Xuthus was a son of King Hellen of Thessaly and the nymph Orseis; and brother of Dorus, Aeolus, Xenopatra^[2] and probably Neonus. He had two sons, Ion and Achaeus,^[3] and a daughter named Diomede by Creusa, the Athenian daughter of King Erechtheus. Euripides's play, Ion, provided an unusual alternate version, according to which Xuthus was the son of Aeolus^[4] and Ion was in fact been begotten on Xuthus's wife Creusa by Apollo. Xuthus and Creusa visited the Oracle at Delphi to ask the god if they could hope for a child, at which point they are told they already have a child, Ion, who was father by Apollo and mothered by Creusa, though Creusa had forgotten her son due to the trauma of being raped by Apollo.^[5] The Oracle at Delphi tells the couple that Ion is Xuthus' son and that Creusa's family should adopt him as Athenian. This makes Creusa so angry she tries to murder her stepson, but she fails. It is at this point the Creusa finds the crib that young Ion slept in and realizes she is his mother.^[6] Despite Ion being adopted, Xuthus is proud to be a father and introduces Ion as his legitimate son to Athens.^[5] Variation's of Xuthus paternity regarding Ion are that he is the true father, that he has been tricked by Apollo and Creusa, or that he has deluded himself into believing he is the father, but the most common version is that told above with the Oracle of Delphi.^[7] Xuthus will later father Dorus and Achaeus with Creusa, though Dorus is normally presented as Xuthus's brother.^[8]

According to the Hesiodic Catalogue of Women on the origin of the Greeks, Hellen's three sons Dorus, Xuthus (with his sons Ion and Achaeus) and Aeolus, comprised the set of progenitors of the major ancient tribes that formed the Greek nation.^[9]

• Apollodorus, The Library with an English Translation by Sir James George Frazer, F.B.A., F.R.S. in 2 Volumes, Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1921. ISBN 0-674-99135-4. Online version at the Perseus Digital Library. Greek text available from the same website.
• Euripides, The Complete Greek Drama, edited by Whitney J. Oates and Eugene O'Neill, Jr. in two volumes. 1. Ion, translated by Robert Potter. New York. Random House. 1938. Online version at the Perseus Digital Library.
• Euripides, Euripidis Fabulae. vol. 2. Gilbert Murray. Oxford. Clarendon Press, Oxford. 1913. Greek text available at the Perseus Digital Library.
• Graves, Robert, The Greek Myths: The Complete and Definitive Edition. Penguin Books Limited. 2017. ISBN 978-0-241-98338-6, 024198338X.
• Grimal, Pierre, The Dictionary of Classical Mythology, Wiley-Blackwell, 1996. ISBN 978-0-631-20102-1. Internet Archive.
• Hard, Robin, The Routledge Handbook of Greek Mythology: Based on H.J. Rose's "Handbook of Greek Mythology", Psychology Press, 2004. ISBN 978-0-415-18636-0. Google Books.
• Hesiod, Catalogue of Women from Homeric Hymns, Epic Cycle, Homerica translated by Evelyn-White, H G. Loeb Classical Library Volume 57. London: William Heinemann, 1914. Online version at theio.com.