The Furies (Erinyes) are fearsome, unforgiving bringers of retribution and exacters of vengeance, particularly against those who wrong their kin (@Oedipus??). 

These winged goddesses, swirled by serpents, represent an inhuman form of justice, the absolute, merciless force of gods. Blood for blood, an eye for an eye. They cast madness, sickness, or simply death. In Aeschylus’ Eumenides (meaning “The Kindly Ones”, often spoken in appeasement or fear), they hound Orestes across the land for killing his mother Clytemnestra. 

The Sphinx is a lion-bodied, eagle-winged, woman-headed monster with a snake-tail that terrorized Thebes. She was the reason King Lauis went to Delphi for a prophecy, clashed with Oedipus on the road, and got killed by his son. Oedipus arrived at Thebes and solved the riddle of the Spinx. The Sphinx flung herself from the cliff on which she was perched, and was gone. Oedipus thus was hailed as the savior and the King of Thebes.

Her riddle was: "What walks on four feet in the morning, two in the afternoon and three at night?". Oedipus answered: "Man: as an infant, he crawls on all fours; as an adult, he walks on two legs and; in old age, he uses a walking stick".