Oedipus Rex, also known by its Greek title, Oedipus Tyrannus, or Oedipus the King, is an Athenian tragedy by Sophocles that was first performed around 429 BC. Originally, to the ancient Greeks, the title was simply Oedipus (Οἰδίπους), as it is referred to by Aristotle in the Poetics. It is thought to have been renamed Oedipus Tyrannus to distinguish it from Oedipus at Colonus, a later play by Sophocles. In antiquity, the term "tyrant" referred to a ruler with no legitimate claim to rule, but it did not necessarily have a negative connotation.

Tragedy is a genre of drama based on human suffering and, mainly, the terrible or sorrowful events that befall a main character. Traditionally, the intention of tragedy is to invoke an accompanying catharsis, or a "pain [that] awakens pleasure,” for the audience. While many cultures have developed forms that provoke this paradoxical response, the term tragedy often refers to a specific tradition of drama that has played a unique and important role historically in the self-definition of Western civilization. That tradition has been multiple and discontinuous, yet the term has often been used to invoke a powerful effect of cultural identity and historical continuity—"the Greeks and the Elizabethans, in one cultural form; Hellenes and Christians, in a common activity," as Raymond Williams puts it.