In Greek mythology, Pittheus (Ancient Greek: Πιτθεύς) was king of Troezen in Argolis, son of Pelops, father of Aethra, and grandfather and early tutor of Theseus. Euripides and Plutarch praise his piety and wisdom — especially his skill with oracles — and Troezenian tradition remembered his tomb and judgment seat into later times.
Adapted from Wikipedia, "Pittheus" · CC BY-SA 4.0
I.King of Troezen
With his brother Troezen, Pittheus came from Pisatis in Elis to the Argolid, shared power with the local king Aetius, and after Troezen's death united Hyperea and Anthea into a single city renamed for his brother. He was famed for eloquence and sententious wisdom; Aristotle and Plutarch even ascribe to him a Hesiodic-style maxim on keeping pledges to a friend.
Bellerophon once sought Aethra's hand at Troezen but was banished from Corinth before the marriage.
II.Aegeus, Aethra, and Theseus
Childless Aegeus of Athens, puzzled by Delphi's wine-skin oracle, consulted Pittheus. Understanding that Aegeus would beget a famous son, Pittheus made him drunk and arranged a night with Aethra — who that same evening had lain with Poseidon. Theseus was thus claimed as son of both the Athenian king and the sea-god. Pittheus raised and instructed the boy; a Troezenian tale has the seven-year-old attack Heracles' discarded Nemean lion-skin with an axe while other children fled.
When Theseus set out for Athens, Pittheus urged the safer sea route, describing the land brigands in vain — the hero chose the Isthmus road in emulation of Heracles. Later Theseus sent his son Hippolytus to Pittheus to be reared as Troezen's heir, until the Phaedra tragedy destroyed that line.