Orestes is the son of Agamemnon and Clytaemestra. Since Greek tragedies never used more than three actors for all speaking roles, the part of Orestes was likely played by the same actor who played the Nurse and Aegisthus. In the play, Orestes is portrayed as a young man just entering manhood. He grieves for the loss of his father Agamemnon, whom he greatly reveres. He is intent on avenging his father’s murder, even though this means he will have to kill his own mother Clytaemestra. Orestes hates his mother because she killed his father and because she banished him from Argos, denying him his rightful inheritance.

Orestes’s determination to kill his mother stems above all from a divine command he received from the god Apollo, who told him that he must avenge his father or suffer severe punishment. Though he comes across as resolute and determined in the first part of the play, a change comes over Orestes when he finally confronts his mother: Faced with what he must do, Orestes realizes that his conscience is hesitant to kill his mother, despite his hatred and despite the commands of Apollo. Orestes finally kills Clytaemestra, feeling that he has no choice, but he feels terrible guilt for his crime and realizes that his obedience to the god Apollo will not prevent him from being punished by the Furies for the murder.