The Harpies were fierce, filthy, winged monsters who had characteristics of a bird and a woman, similar to that of the early Sirens. Their hideous faces of women with sharp claws mounted on the bodies of vultures inspired both horror and disgust. They could fly as fast as a bolt of lightening.
The three daughters of Thaumas and Electre called Aello, Ocypete, and Celaeno were originally goddesses with beautiful hair and wings until they were reduced to such fearsome monsters.They were also referred to as "robbers," "snatchers," and "those who seize," meaning that they would steel anything that did not belong to them. They snatched food from their victims or left a loathsome stench rendering it unedible. They were also referred to as the "hounds of Zeus."
They serve Zeus. They are sometimes represented as demons of death carrying away the souls of deceased persons (see the Haryp tomb in the British Museum).The people feared them for it was said that they stole small children and carried away the weak and the wounded.
One of the most famous stories involves Phineus, the King of Thessaly, who had the gift of seeing into the future. Phineus told Zeus' secrets to others and Zeus took away his sight and sent the Harpies, the "hounds of Zeus," to come after him. The Harpies kept steeling his food and devouring it for themselves and leaving only enough for Phineus to survive. When Jason and the Argonauts visited Phineus, Zetes and Calais, sons of the North Wind, pursued the Harpies through the sky. Iris or Hermes convinced Zeus to remove the Harpies from Phineus.