The Oresteia Trilogy is a series of three ancient Greek tragedies written by Aeschylus, consisting of 'Agamemnon,' 'The Libation Bearers,' and 'The Eumenides.' This trilogy explores themes of justice, revenge, and the evolution of societal norms in the context of familial duty and divine influence. It is notable for its complex characters and moral dilemmas, which illustrate the transition from personal vengeance to legal justice.