In Greek mythology, the Sphinx is a treacherous and merciless being with the head of a woman, the haunches of a lion, and the wings of a bird. She challenges those who encounter her to answer a riddle, and kills and eats them when they fail to solve the riddle. This deadly version of the Sphinx appears in the myth and drama of Oedipus.

The Sphinx is said to have guarded the entrance to the Greek city of Thebes, asking a riddle to travellers to allow them passage. The exact riddle asked by the Sphinx was not specified by early tellers of the myth, and was not standardized as the one given below until late in Greek history.

It was said in late lore that Hera or Ares sent the Sphinx from her Aethiopian homeland to Thebes, where she presented all passers-by with this riddle: “Which creature has one voice and yet becomes first four-footed, then two-footed, then three-footed?” She strangled and devoured anyone who could not answer. Oedipus solved the riddle by answering: “Man, who crawls on all fours as a baby, then walks on two feet as an adult, and then uses a walking stick in old age”.