In Greek mythology, Xuthus // or // (Ancient Greek: Ξοῦθος) was a son of Hellen and Orseis and founder (through his sons) of the Achaean and Ionian nations. He had two sons by Creusa: Ion and Achaeus and a daughter named Diomede.
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.
Aiclus and Cothus are sometimes described as being his children. Euripides's play, Ion, provides an unusual alternate version, according to which Xuthus is son of Aeolus and Cyane and Ion has 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. Xuthus will later father Dorus with Creusa, though Dorus is normally presented as Xuthus's brother.
- Hesiod, Catalogue frr. 9, 10(a).