King Pittheus was a legendary figure in Greek mythology, known as the ruler of Troezen. He was the son of Pelops and Hypsipyle, and he played a significant role in the myth of Theseus. Pittheus is often remembered for his wisdom and his ability to interpret oracles. One of his most notable actions was the fathering of Theseus with Aethra, who was the daughter of Pittheus. According to the myths, Pittheus helped Aethra conceive Theseus by instructing her to sleep with Poseidon and Aegeus, the king of Athens, thus ensuring Theseus's heroic lineage.