Pluto is how the god of the dead and riches became known in Roman Mythology, after the introduction of Greek myths and literature. Originally, the Romans did not have a notion of a realm for after-death happiness or unhappiness, like the Greek Hades - but an immense cavity, called Orco, which later came to be identified with the Greek underworld.
To the god who commanded him, then, they incorporated Hades, under his epithet of Pluto. He was also responsible for everything that lies beneath the earth.
He was the son of Saturn (Cronos) and Rhea and brother of Jupiter and Neptune. When Jupiter shared the Universe, he gave Pluto the empire of the underworld. Pluto was so macabre and frightening, he couldn't find a woman who would accept him to marry.
So he decided to steal Proserpina, daughter of Jupiter and Ceres-goddess of agriculture-when she was on her way to the spring of Arethusa, in Sicily, to fetch water. Pluto is represented with an ebony crown on his head, the keys to hell in his hand, in a coach drawn by black horses.
Pluto was, the God of Greek Mythology, Hades.