Hades

Greek (ha'-dez) (Haides, haides, "not to be seen"): Hades, Greek, originally Haidou, in genitive, "the house of Hades," then, as nominative, designation of the abode of the dead. (Compare Hebrew, She'Ol, "unseen," also the abode of the dead). 

Also, Hades, God of the underworld, so named because he was given the unseen kingdom of that name (which predates the god, Hades, in Greek mythology). Brother of [[Zeus]].  In Greek mythology, The three brothers Zeus, [[Poseidon]] and Hades drew lots for realms to rule.  Zeus got the sky, Poseidon got the seas, and Hades received the Underworld, or the unseen realm to which the dead go upon leaving the world, as his kingdom. His kingdom was entered by crossing the river Styx, ferried accross by [[Charon]] (pronounced Karon). The far side of the river was guarded by [[Cerebus]], the three headed dog defeated by [[Herecles]] (or [[Hercules]] as the Romans referred to him).  Hades obtained his eventual wife, [[Persephone]], through trickery.

Hades was a fearsome figure to those still living, and who were in no hurry to meet him, so they were reticent to swear oaths in his name. To many, simply to say the word "Hades" was frightening. So, A euphemism was pressed into use. Since precious minerals come from under the earth (ruled by Hades) he was referred to as "Ploutos", Greek "wealth." This explains the name given him by the Romans, "Pluto."