In Greek mythology and history, Achaeus is the name of several individuals.

• The founder of Achaean race. He was a son of Xuthus and Creusa. He fled Thessaly, after the accidental murder of a man, to Peloponnesus. His sons and the inhabitants of the area were called after him. He later returned to Thessaly.
• A king of Lydia who was hanged by his subjects for extortion, according to Ovid.
• Achaeus, a tragic poet of Eretria who wrote forty-five tragedies, some of whose titles are preserved (e.g. Adrastus, Linus, Cycnus, Eumenides, Philoctetes, Pirithous, Theseus, OEdipus, etc.). Only one of these won the prize in competition. He lived some time after Sophocles.
• Another tragic poet of Syracuse, who wrote ten tragedies.
• A relative of Antiochus III the Great who was appointed governor of all the king's provinces beyond Taurus. He aspired to be king and fought with Antiochus for eight years. He was at last betrayed by a Cretan. His limbs were cut off, and his body, sewed in the skin of an ass, was exposed on a gibbet.

--This article incorporates some material from the public domain 1848 edition of Lempriere's Dictionary.