Aethra was Theseus’s mother in Greek mythology. She was the daughter of King Pittheus of Troezen and became connected with both Aegeus, king of Athens, and the god Poseidon in different versions of the myth.
According to the traditional story, Aegeus left a sword and sandals beneath a great stone and told Aethra that their son should retrieve them when he was strong enough. Theseus later lifted the stone, claimed the identifying objects, and traveled overland to Athens.
This origin story explains why Theseus was recognized as Aegeus’s son and why he became an Athenian prince before undertaking the Cretan adventure. Some ancient accounts give Poseidon a divine role in Theseus’s parentage, creating a deliberate double-paternity tradition.
Aethra is sometimes confused with Ariadne or Phaedra. Ariadne helped Theseus in Crete, while Phaedra was Ariadne’s sister and later became Theseus’s wife.