Styx
Styx is the goddess of the river Styx in Greek mythology, and was the only female river goddess. She was the daughter of Okeanos and Tethys, and with Pallas was also the mother of Zelus, Nike, Kratos, and Bia (and sometimes Eos). During the Titanomachy she sent the children to help Zeus. To reward her for helping the Olympians, Zeus did not throw her in Tartarus, but let her be the guardian of the river Styx. She is the wife of the ferryman, Charon, and the guardian of the river Coctylus, Archeon.