Tiestes, in Greek mythology, is one of the brothers of Atreus and the father of Pelopia and Aegistus.
Atreus and Tiestes were sons of Pelope and Hippodamia. Pelope was the son of either the son of Tantalus and Dione, or of Tantalus and Eurianassa. Hippodamia was the daughter of Enomau and Evarete.
Enomau challenged every suitor of his daughter Hippodamia to a chariot race, and killed them during the race, but Pelope got Myrtilus, Enomau's charioteer, to sabotage his chariot, winning the race and winning the hand of Hippodamia; Pelope, however, killed Myrtilus, who cursed Pelope and his offspring.
Hippodamia convinced Atreus and Thiestestes, her sons, to murder Crisippus, the son of her husband Perlops with the nymph Axioch. According to one version, Hippodamy committed suicide when Perlops blamed her for the crime. After the crime, she and her two sons were cast out, where they were taken in by Eurystheus in Mycenaeus and Midea, where Hippodamy later committed suicide.
Dispute over Mycenae
Eurystheus died fighting the Heraclids, and Atreus and Tiestes became kings of Mycenae.
Atreus wanted to offer his best lamb as a sacrifice to Artemis. While searching his flock, he discovered a golden lamb, which he offered to his wife, Aérope, to hide it from the gods. But she gave the lamb to her lover, Tiestes, Atreus' brother.
The latter says that whoever has the golden lamb should be king. Atreus accepts, but Tiestes appears with the lamb and claims the throne. But Atreus, on the advice of Hermes, challenges Tiestes to give him the throne if the sun goes backwards. Tiestes agrees, Zeus sets the sun going backwards in the sky, and Atreus regains the throne and drives Tiestes out of Mycenae.
Revenge of Atreus
When Atreus discovered his wife's infidelity, he wanted to take revenge and invited Tiestes to a banquet under the pretext of a supposed reconciliation. When the meal was over, Atreus showed Tiestes that the food served to him was meat from his own children and expelled Tiestes from Mycenae.
Tiestes' sons, whom he had with a naiad, were named Aglaus, Callieon, and Orcomene.
Rape of his own daughter
On the advice of an oracle, who said that a son of his with his daughter would avenge Atreus, he had a son, Egistus, with his daughter.
According to another version, in disguise, Tiestes raped Pelopia, his daughter, who managed to keep the rapist's sword. Atreus, who married Pelopia without knowing that she was Tiestes' daughter, adopted Pelopia's son, who had been abandoned in the mountains, but was recovered by a shepherd and given to Atreus. Atreus forgave Pelopia and named the child Egistus.
When Egistus grew up and discovered that he was the son of Tiestes, he killed Atreus and restored Mycenae to Tiestes.
According to another version, Atreus' sons later managed to imprison Tiestes and Atreus ordered Egistus to kill him. However, he was overpowered by Tiestes and recognized Egistus' sword as his own.
He then told him the whole story and ordered his son to call Pelopia, who upon learning that Egystus' real father was Tiestes, committed suicide. Ordered by his father, Egistus murdered Atreus, fulfilling the oracle's prediction, after Tiestes revealed to him that he was Egistus' true father.
End of the reign
Agamemnon and Menelaus managed to escape from Mycenae, being taken by the sitter to Polyphides, king of Sicily, who delivered them to Aeneus of Aetolia.
Tyndareus brought Agamemnon and Menelaus back, expelled Tiestes, and exiled him to Scythia, after Tiestes had fled to an altar of Hera and had taken an oath. Agamemnon married Clytemnestra, and killed her husband, Tantalus, son of Tiestes, and the newborn son of Tantalus and Clytemnestra.
Descendants of Thiestes
Clitemnestra, Agamemnon's wife, betrayed him with Aegistus; as soon as Agamemnon arrived in Mycenae with Cassandra, Clitemnestra gave him as a gift a shirt that had no sleeves, and when he put it on, he was killed, and Aegistus came to reign.
Electra, Agamemnon's daughter, got Orestes, her brother, to escape, the latter later returned with Pilades, and killed both Egistus and his own mother Clytemnestra.