In Greek mythology, Theoclymenus, son of Polypheides, was a prophet from Argos, who in the Odyssey had been exiled from that city after killing one of his relatives. He fled to Pylos and sought refuge with Telemachus, who had come there to inquire about the fate of his father Odysseus.

He accompanied Telemachus back to Ithaca where he read the auspices of the birds, interpreting to mean Telemachus would become head of the royal house of Ithaca. He also prophesied that Odysseus was already in Ithaca, disguised and watching events unfold. When he told Penelope of these signs she did not believe him. Later at dinner he had a vision of the death of the suitors, but they laugh at his predictions, not knowing they would indeed be killed that night.

Theoclymenus is also the name of the king of Egypt in Euripides' play Helen.