What is a Sphinx? (mythology)

Egyptian sphinx
  Sphinx, in Greek mythology, a composite monster having the head of a woman, the body of a lion, and the wings of a bird. According to legend she proposed a riddle to the Thebans, slaying all who were unable to guess it. The riddle was "What is it which has four feet in the morning, two at noon, and three at night?" When Oedipus solved the riddle by answering "Man", the sphinx threw herself over a cliff and perished. The name "sphinx" was also applied by the Greeks to a class of ancient Egyptian composite figures having the body of a lion and the head of some other animal or of a man, frequently a portrait of a king; the Greek mythological sphinx was probably derived from these figures. The most remarkable of all Egyptian sphinxes is the Great Sphinx of Giza, situated about 300 feet east of the second pyramid, and thought to have been built to protect the neighboring tombs from evil spirits. It is a colossal image of Harmachis, Egyptian god of the rising sun, and is believed to date from about 2850 B.C., during the reign of King Khafre of the IVth dynasty. It is hewn out of a rocky promontory and built up with masonry to correct the natural outline. Its measurements, which vary according to the drift of the sand around the statue, are, as computed by the British Egyptologist Sir William Matthew Flinders Petrie, 189 feet in length and 70 feet in height, and 30 feet from forehead to chin. Sphinxes are also found in Assyrian, Minoan, Roman, and Mayan cultures.