Gray Sisters

The Gray Sisters are a trio of old women who share among them a single eye and a single tooth. They are known as Anger (Deino), Tempest (Persis or Perso) and Wasp (Pempherdo). They are the operators of a taxi firm which services the Greater New York City and environs in Percy Jackson and the Olympians:The Sea of Monsters. They are the daughters of Keto and Phorkys (or Phorcys), the sisters of the Gorgons, Ladon and Echidna.

The Sea of Monsters
In the Sea of Monsters, Annabeth hails the Gray Sisters' service when she, Percy and Tyson are running from the authorities after Percy is blamed for "torching" the school gym at Meriwether Prep.They drove them to Camp Half Blood. Before reaching Camp Half-Blood, however, they fought over their single eye and single tooth (So that they could see, drive, and speak). They are also wise in strange ways and know where things are.

See also:

 * Gray Sisters' Taxi