Styx was one of the Titans in greek mythology. She was the daughter of the sea Titans Oceanus and Tethys. She was the Titan of the Underworld river named after her, and was the embodiement of hatred and detestation.

Styx represented and controlled hatred. This made her one of the most feard Titans. During the "Golden Age" of the Titans, she was the guardian of the Underworld. Before the war, she was married to her cousin Pallas, son of Crius and Eurybia. However, Pallas was killed during the war. Throughout most of the war, she was neutral, like her parents and siblings, the River gods and Ocean nymphs. During the last battle of the Titan War, she chose to side with Zeus and the Olympians, giving her four children, Bia (goddess of force), Kratos (god of Power), Zelus (god of Zeal) and Nike (goddess of Victory) in his service. She was greatly rewarded for her allegiance. 

The greatest oath that a god can make is to swear on the River Styx. When a God swears on the River Styx, their bound for all eternity to keep that promise or else be paralysed for a year and a day, and even then, risk being ostracized from Mount Olympus and their duties and immortality being removed andgiven to another god.