The Oresteia, a trilogy of Greek tragedies written by Aeschylus. The name derives from the character Orestes, who sets out to avenge his father's murder.The only extant example of an ancient Greek theater trilogy, the Oresteia won first prize at the Dionysia festival in 458 BC. Principal themes of the trilogy include the contrast between revenge and justice, as well as the transition from personal vendetta to organized litigation.