In Greek mythology, Idomeneus was a Cretan warrior, grandson of Minos. 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.

After the war, his ship hit a horrible storm. Idomeneus 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 him in exile to Calabria in Italy. (Virgil III, 400)

In an alternate version, his own subjects on Crete sent him in exile because he brought a plague with him from Troy. He fled to Calabria, and then Colophon, Asia Minor, where he died.

Idomeneo, a 1780 opera seria by Mozart is based on the story of Idomeneus.