What creature does Oedipus defeat to become king?

Oedipus defeats the Sphinx to become king, which is a pivotal moment in the narrative. The Sphinx is a mythical creature known for posing riddles to travelers and devouring those who cannot answer correctly. When Oedipus encounters the Sphinx, he is presented with her riddle, which is famously known as "What walks on four legs in the morning, two legs at noon, and three legs in the evening?" Oedipus correctly answers that it is a human, who crawls as a baby (four legs), walks upright as an adult (two legs), and uses a cane in old age (three legs).

This victory not only showcases Oedipus's intelligence and cunning but also frees the city of Thebes from the Sphinx's terror. This accomplishment earns him the throne and the hand of Jocasta, the widow of the former king, setting the stage for the tragic unfolding of events that define the rest of the play. The significance of this moment emphasizes themes of fate, knowledge, and the inherent complexities of human existence, which are central to the overall tragedy in "Oedipus Rex."