Harpy

Harpies (meaning "snatcher", from Latin: harpeia, originating in Greek: ἅρπυια, harpūia), winged spirits beast known for constantly stealing all food from Phineas, but were driven away by Calais and Zethes, the boreads, and since they lived on the strophades. The literal meaning of the word seems to be "that which snatches" as it comes from the ancient Greek word harpazdein (ἁρπάζειν), which means "to snatch".

Percy Jackson and the Olympians
In the Percy Jackson series at Camp Half-Blood, there are cleaning harpies and harpies that come to eat demigods that are sneaking out of their cabins at night. They refer to themselves in the third person, as in "Campers out of bed! Dinner for hungry harpies!"

The Son of Neptune
A harpy named Ella appears in The Son of Neptune. She's one of the three harpies who snatch food from Phineas picknick table. She's faster and more nimble than her two sisters. When befriending with Percy, Hazel and Frank, she shows her ability to memorize a massive amount of facts she reads in books. Percy decides that they have to free the harpies from their curse (to be only able to eat from Phineas' table) which they accomplish with a gamble to the death, including Percy and Phineas both drinking Gorgon Blood, not knowing which vial was from which side of the monster. Later on, Ella is taken to camp Jupiter by Tyson.

Family
A harpy was known as the mother of Zephyrus, the west wind, sisters of Iris and daughters of Thauma, and Electra.

Occupation
Phineas, a king of Thrace, like Apollo, had a gift of prophecies. Zeus was angered by the information he was revealing that he sealed him away to a island with buffet of food that Phineas could never eat. The Harpies would always snatch the food from him and take it away, leaving Phineas to starve.

In The Son of Neptune however, when Phineas was revived by Gaea, the tables have turned and Phineas is now the one to eat the food and be able to keep the harpies from his table though they are bounded to eat and can't consume any other food.

Trivia

 * The American Harpy Eagle is a bird named after them.