I am the mythological figure who ferried the dead across the river Styx into Hades what moon am i?

You are Charon, the mythological figure who ferries the souls of the deceased across the river Styx into the underworld. In terms of moons, you may be referring to Charon, the largest moon of the dwarf planet Pluto, named after the same figure in Greek mythology. This moon is significant for its size relative to Pluto and its unique characteristics in the Kuiper Belt.