Jocasta was, in Greek mythology, the daughter of Mencedus and wife of Laius, king of Thebes, with whom she had a son, Oedipus.
Laio received an oracle from Delphi which told him that he must not have a child with his wife, or the son would kill him and marry her; in another version, recorded by Aeschylus, Laio is warned that he can only save the city if he dies childless. One night, Laius got drunk and fathered Oedipus with Jocasta.
Jocasta passed the newborn baby to Laio. Jocasta or Laio pierced and bound the baby's ankles together. Laius instructed his chief shepherd, a slave born in the palace, to expose the child on the hill of Montserrat.
Laius' shepherd took pity on the baby and gave him to another shepherd in the service of King Polybus of Corinth. Childless, Polybius and his queen, Meredope (according to Sophocles], or Peribea (according to Pseudo-Apolodorus), raised the baby to adulthood.
As an adult, Oedipus, on one of his pilgrimages to the Oracle, discovers that he will be the murderer of his father, and so he flees his city and his fate. However, halfway there he comes across a carriage carrying the king of Thebes, Laius.
One of his servants throws the carriage against Oedipus, who, overcome by anger at the pride of the members of the entourage and of the king he doesn't know, fights against those people until he wins his "honor" with the death of those men.
Only one of the servants manages to escape. When he arrives in Thebes, he sees that the city - polis - is being pursued by a great evil, the Sphinx with its enigma. Oedipus is the only one who manages to solve the riddle and is thus proclaimed king of Thebes.
He marries Jocasta, his mother. Some time goes by before news reaches the city of Laius' death. Oedipus, upon hearing the news, tries to find the culprits of the murder and sends his brother-in-law Creon to the oracle of Apollo. Upon his return, Creon tells him that, according to the god, the murderer is among them. Oedipus then proceeds to pursue the murderer indiscriminately.
The citizens, made up of the chorus, suggest that the king call Tyrethias, a soothsayer who claims to be an intermediary between men and the god Apollo. When the latter does not hide the truth from him, Oedipus insults him, calling him a fake, a false prophet.
Then, under pressure, Tyrethias reveals his knowledge. Oedipus would be the murderer. Not believing, Oedipus accuses Tyresias and Creon of treason. He accuses them of planning to usurp the throne. Creon, upon learning of such allegations against his person, comes to the king so that the confusion may be cleared up. Oedipus does not listen to him.
Jocasta intervenes on behalf of her brother. Faced with Creon's oath and his argumentative speech, Oedipus is lost. Jocasta, without further pretension, tells him some facts about the death of Laius that Oedipus did not know. Faced with the new narrative, he then begins to wonder whether he himself might not be the murderer.
Oedipus asks for the servant of the surviving Laius to be called. Meanwhile, news arrives, through a messenger, of the death of Oedipus' adoptive father. This messenger is the same shepherd who had saved him from death. He tells him all about what happened.
Another shepherd then comes to the kingdom and after much reluctance, tells Oedipus the truth. Jocasta, faced with what had happened, hangs herself in her room. Oedipus, upon seeing this scene, blinds himself as a punishment for having consummated the marriage with his mother and killed his father. In the end, Oedipus asks Creon to send him away from the city so that he can live in exile, away from his shame.
Oedipus and Jocasta had four children, Antigone, Ismenia, Aethole, and Polynices.