In Greek mythology, Idomeneus ( /aɪˈdɒmɨniːəs/; Greek: Ἰδομενεύς, Idomeneus, "strength of Ida") was a Cretan warrior, father of Orsilochus, Cleisithyra, Leucus and Iphiclus, son of Deucalion and Cleopatra, grandson of Minos and king of Crete. He led the Cretan armies to the Trojan War and was also one of Helen's suitors. Meriones was his charioteer and brother-in-arms. In Homer's Iliad, he is found among the first rank of the Greek generals, leading his troops and engaging the enemy head-on, and escaping serious injury. Idomeneus was one of Agamemnon's trusted advisors. He was one of the primary defenders when most of the other Achaean heroes were injured, and even fought Hector briefly and repulsed his attack. Like most of the other leaders of the Greeks, he is alive and well as the story comes to a close. He was one of the Achaeans to enter the Trojan Horse. Idomeneus killed thirteen men and at least one Amazon woman, Bremusa at Troy.
According to the fourth century Italian writer Maurus Servius Honoratus, and the French 17th century writer François Fénelon, the story continues as follows: after the war, Idomeneus's ship hit a terrible storm. He promised Poseidon that he would sacrifice the first living thing he saw when he returned home if Poseidon would save his ship and crew. The first living thing was his son, whom Idomeneus duly sacrificed. The gods were angry at his murder of his own son and they sent a plague to Crete. The Cretans sent him into exile in Calabria, Italy and then Colophon in Asia Minor where he died. According to Marcus Terrentius Varro, the gens Salentini descended from Idomeneus, who had sailed from Crete to Illyria, and then together with Illyrians and Locrians from Illyria to Salento, see Grecìa Salentina.
Alternatively, Idomeneus was driven out of Crete by Leucus, who had seduced and then killed Idomeneus' wife Meda and usurped the throne of Crete.
According to the hypothetical reading of Achterberg et al. (2004), Idomeneus may be mentioned on the Phaistos Disk (spelled i-du-ma-na, word B.IX) as the governor of Mesara.
Idomeneo, a 1781 opera seria by Mozart, is based on the story of Idomeneus's return to Crete. In this version, Poseidon (Neptune in the opera) spares Idomeneo's son Idamante, on condition that Idomeneo relinquish his throne to the new generation.