Styx is named after the river forming a boundary between Earth and the Underworld in Persian cosmology.
According to some versions, the river Styx had miraculous powers which could make someone who bathed in the waters invulnerable
 Dante, putting Charon and the Acheron at the entrance to Hell, put Phlegyas as ferryman over the Styx and made it the fifth circle of Hell, where the wrathful and sullen are punished by being drowned in the muddy waters for eternity, with the wrathful fighting each other

