In Greek mythology, Jocasta, also Iocaste or Epikastê, was a daughter of Menocenes. She was the wife of Laius and, by him, mother (and wife) of Oedipus, and mother (by Oedipus) of Antigone, Eteocles, Polynices and Ismene.

Her husband, King Laius of Thebes, consulted an oracle when she was pregnant with her first child, Oedipus. The oracle claimed he was destined to kill his father and marry his own mother. Laius had the baby left out in the woods to die. He was found by a shepherd and given to King Polybus and Queen Merope (or Periboea) of Corinth.

Later, Oedipus killed Laius, not knowing who he was, and married Jocasta, not knowing who she was. When this was discovered, Oedipus tore out his own eyes with Jocasta's brooch and Jocasta committed suicide by hanging.

Homer Odyssey Book 11

"The next I saw was Oedipus' mother,
fair Jocasta, who, against her knowledge,
undertook a monstrous act—she married
her own son. Once he'd killed his father,    
he made her his wife. And then the gods
showed everyone the truth.  But Oedipus,
thanks to the fatal counsels of the gods,
for all his painful suffering, remained king
in lovely Thebes, ruling the Cadmeans.
But she descended down to Hades' home,
the mighty goaler.  She tied a fatal noose
to a roof-beam high above her head and died,
overwhelmed with grief.  But she left behind
enormous agonies for Oedipus,  
all that a mother's Furies can inflict.   

In astronomy, Iocaste is the name of a small moon of the planet Jupiter.