Orestes is the son of the murdered King Agamemnon and Queen Clytaemestra. Forced into exile as a child, he returns to Argos as a young man under orders from the god Apollo to exact vengeance for his father's death. He feels a deep sense of duty to reclaim his rightful inheritance and honor his father's memory, though this mission requires him to punish his own mother.

Electra is the daughter of Agamemnon and Clytaemestra. She lives in a state of perpetual mourning and near-servitude within her own home following her father's murder. She intensely dislikes her mother and Aegisthus, placing all her hopes for deliverance on her brother Orestes's eventual return to Argos.

Clytaemestra is the queen of Argos who previously murdered her husband Agamemnon and seized power with her lover Aegisthus. She maintains her position by banishing her son Orestes and subjecting her daughter Electra to a harsh life. An ominous dream prompts her to seek appeasement from the spirit of the husband she betrayed by sending offerings to his tomb.

Aegisthus is the current ruler of Argos and Clytaemestra's husband. He assisted in the murder of the previous king to settle a generational blood feud between his father, Thyestes, and Agamemnon's father, Atreus. He currently enjoys the spoils of this usurpation while keeping Agamemnon's heirs suppressed or exiled.

The Chorus consists of enslaved Argive women who serve the royal household. Despite being ordered by the queen to pour offerings, their true loyalty lies with the murdered king and his marginalized children. They actively guide Electra's prayers and encourage the desire for retribution against the current rulers of Argos.

Agamemnon is the deceased king of Argos and former commander of the Greek forces at Troy. Though he is dead before the play begins, his spirit and the manner of his violent death heavily influence the actions of the living characters. His children view him as a great, unjustly murdered hero whose blood demands payment.

Pylades is Orestes's close friend and traveling companion. He journeys to Argos to support Orestes in his divinely mandated mission to reclaim his home and avenge his father. He provides steady, silent support during the siblings' reunion and the early stages of their planning.

Cilissa is an elderly servant in the Argive palace who previously served as Orestes's wet nurse. She maintains a deep, genuine affection for the boy she raised, contrasting sharply with the coldness of his biological mother.

Apollo is the god of prophecy who commands Orestes to return to Argos and avenge Agamemnon's murder. He enforces this mandate with threats of severe punishment if Orestes fails, establishing the divine pressure that drives the young prince's violent actions.