Lord of the Underworld.
Pluto is the Roman God of the underworld (Hades) and is the son of Saturn (Titan) and Rhea. In Greek he is Hades, son of Cronus and Rhea. He was the third brother of the Olympians. He was also known as God of Wealth, and precious metals hidden in the earth.
He was often translated into the name Dis meaning wealth, and he wore a helmet which made those who wore it invisible, and rarely left the underworld. Greeks also called him Thanatos the name of the god of death who was overshadowed by Pluto, and the Romans called him Orcus.
Pluto took Proserpina (Persephone) for a wife, from her mother Ceres (Demeter). A deal was formed to allow Pluto to keep Proserpina as Queen of the underworld for half of the year and for her to return to her father Jupiter and her mother Demeter in the other half. This explains the story of the seasons. When Proserpina is with her parents, it is spring and summer because she is happy. When it is winter and fall, it is cold and gloomy because Proserpina must leave her parents, and she becomes saddened.