In Greek mythology, Orestes (in English /ɔ'ɹɛstiːz/, and in Greek, Ὀρέστης) was the son of Clytemnestra and Agamemnon. He is the subject of several Ancient Greek plays and of various legends connected with his madness and purification. The surviving Greek myths that include Orestes are obscure, but retain threads of much older ones.
Orestes originates from the word oreivates (Greek "ορειβάτης") which directly translates to mountaineer. The metaphoric meaning is the person who can conquer mountains.
In the Homeric story, Orestes, a member of the doomed house of Atreus which is directly related to Tantalus and Niobe, was absent from Mycenae when his father, Agamemnon, returned from the Trojan War with Cassandra, a Trojan Princess, as his concubine, and was murdered with an axe by his wife, Clytemnestra, in retribution for his sacrifice of his daughter Iphigeneia to obtain favorable winds to Troy for the Greek fleet. Eight years later, Orestes returned from Athens and with his sister Electra avenged his father's death by slaying his mother and her lover Aegisthus.
According to Pindar, the young Orestes was saved by his nurse Arsinoe or his sister Electra, who conveyed him out of the country when Clytemnestra wished to kill him. In the familiar theme of the hero's early eclipse and exile, he escaped to Phanote on Mount Parnassus, where King Strophius took charge of him. In his twentieth year, he was urged by Electra to return home and avenge his father's death. He returned home along with his friend Pylades, Strophius's son.
In The Greek Myths the mythographer and poet, Robert Graves, translates and interprets the legends and myth fragments about Clytemnestra, Agamemnon, and Orestes, as suggesting a ritual killing of a "king" (Agamemnon) in very early religious ceremonies that were suppressed when patriarchy replaced the matriarchies of very ancient Greece and, that the sacrilege for which the Erinyes pursued Orestes, was the killing of his mother, who represented matriarchy. He explains that worship of Athena was retained as a cult because it was too strong to be suppressed, but she was recast as a child of Zeus and in new myths, even given the previously incomprehensible role of justifying what would have been a horrific crime against the old religious customs. Graves, and many other mythographers, were influenced by The Golden Bough of James Frazer and, since it was published many myths have been reinterpreted to reveal clues to ancient religious practices that were kept as secret rituals.
In Aeschylus's Eumenides, Orestes goes mad after the deed and is pursued by the Erinyes, whose duty it is to punish any violation of the ties of family piety. He takes refuge in the temple at Delphi; but, even though Apollo had ordered him to do the deed, he is powerless to protect Orestes from the consequences. At last Athena receives him on the acropolis of Athens and arranges a formal trial of the case before twelve Attic judges. The Erinyes demand their victim; he pleads the orders of Apollo; the votes of the judges are equally divided, and Athena gives her casting vote for acquittal. The Erinyes are propitiated by a new ritual, in which they are worshipped as Eumenides, and Orestes dedicates an altar to Athena Areia.
As Aeschylus tells it, the punishment ended there, but according to Euripides, in order to escape the persecutions of the Erinyes, Orestes was ordered by Apollo to go to Tauris, carry off the statue of Artemis which had fallen from heaven, and to bring it to Athens. He went to Tauris with Pylades, and the pair are at once imprisoned by the people, among whom the custom was to sacrifice all Greek strangers to Artemis. The priestess of Artemis, whose duty it was to perform the sacrifice, was Orestes' sister Iphigenia. She offered to release him if he would carry home a letter from her to Greece; he refused to go, but bids Pylades to take the letter while he stays to be slain. After a conflict of mutual affection, Pylades at last yielded, but the letter brought about a recognition between brother and sister, and all three escaped together, carrying with them the image of Artemis. After his return to Greece, Orestes took possession of his father's kingdom of Mycenae (killing Aegisthus' son, Alete), to which were added Argos and Laconia. He was said to have died of a snakebite in Arcadia. His body was conveyed to Sparta for burial (where he was the object of a cult), or, according to a Roman legend, to Aricia, when it was removed to Rome (Servius on Aeneid, ii. 116).
Before the Trojan War, Orestes was to marry his cousin Hermione, daughter of Menelaus and Helen. Things soon changed after Orestes committed matricide: Menelaus then gave his daughter to Neoptolemus, son of Achilles and Deidamia. According to Euripides' play Andromache, Orestes slew Neoptolemus just outside a temple and took off with his cousin, Hermione. He seized Argos and Arcadia after their thrones had become vacant, Orestes became ruler of all the Peloponnesus. His son by Hermione, Tisamenus, became ruler after him but was eventually killed by the Heracleidae.
Orestes appears also as a shown to all persons whose crime is mitigated by extenuating circumstances. These legends belong to an age when higher ideas of law and of social duty were being established; the implacable blood-feud of primitive society gives place to a fair trial, and in Athens, when the votes of the judges are evenly divided, mercy prevails.
In The History by Herodotus, the Oracle of Delphi foretold that the Spartans could not defeat the Tegeans until they moved the bones of Orestes to Sparta. Lichas discovered the body, which measured 7 cubits long (around 10 feet, or 3.30 meters.) Thus Orestes would have been a giant.
For modern treatments see the Oresteia in the arts and popular culture.