The main characters in Oedipus Rex, a tragedy written by Sophocles, include:

1. Oedipus - The protagonist and tragic hero of the play. He is the king of Thebes and tries to uncover the truth about his past, which ultimately leads to his downfall.
2. Jocasta - Oedipus' wife and mother. She tries to prevent Oedipus from discovering the truth about his past.
3. Creon - Jocasta's brother and Oedipus' brother-in-law. He is a trusted advisor to Oedipus and becomes the king after Oedipus' downfall.
4. Tiresias - A blind prophet who warns Oedipus about his fate.
5. The Chorus - A group of Theban citizens who comment on the action of the play and provide insight into the themes and events.
6. Laius - Oedipus' biological father, who was killed by Oedipus without either of them knowing their true relationship.
7. Polybus - The man who raised Oedipus as his own son, but who was not his biological father.
8. Merope - Polybus' wife and Oedipus' adoptive mother, who was not his biological mother.