Plouton is how Plato referred to Plouton. Of course, this will be my default address unless substantial data is provided otherwise.
https://en.wikipedia.org/wiki/Pluto_(mythology)
Plouton as the name of the ruler of the underworld first appears in Greek literature of the Classical period, in the works of the Athenian playwrights and of the philosopher Plato, who is the major Greek source on its significance.