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, as it is referred to by Aristotle in the Poetics. It is thought to have been renamed Oedipus Tyrannus to distinguish it from another of Sophocles's plays, Oedipus at Colonus. In antiquity, the term "tyrant" referred to a ruler with no legitimate claim to rule, but it did not necessarily have a negative connotation.