In Greek mythology, Polyxenus or Polyxeinus /pəˈlɪksɪnəs/ (Ancient Greek: Πολύξενος, Poluxenos, or Πολύξεινος, Poluxeinos) is a name that may refer to:

• Polyxenus, one of the first priests of Demeter and one of the first to learn the secrets of the Eleusinian Mysteries.^[1]
• Polyxenus, son of Agasthenes and Peloris, king of Elis. He was counted among the suitors of Helen,^[2] and accordingly participated in the Trojan War, having brought 40 ships with him.^[3] He returned home safely after the war, and had a son Amphimachus, whom he possibly named after his friend Amphimachus (son of Cteatus), who had died at Troy.^[4] Polyxenus, king of Elis, was said to have been entrusted with the stolen cattle by the Taphians under Pterelaus; the cattle was ransomed from him by Amphitryon.^[5] This Polyxenus, however, appears to be a figure distinct from Polyxenus, son of Agasthenes, since he lived two generations before the Trojan War.
• Polyxenus, also called Medus, son of the hero Jason and the Colchian sorceress Medea,^[6] the daughter of King Aeëtes. He was the brother of Eriopis.^[7]