Orestes

"In 458 BCE, Aeschylus staged the Orthasty trilogy. The tragedy culminates in the trial of Orestes, who killed his own mother to avenge his father's death. His acquittal by the Athenian jury put an end to the eye for an eye, tooth for tooth and converted from the Erinias, goddesses of revenge, in Eumenides, as defenders of the democracy, a civilizing landmark in the western culture."