Pluto was the son of Cronus and Rhea who aided his brothers Zeus and Poseidon in deposing Cronus. He obtained the lower regions as his kingdom, ruling over the shades with his queen, Persephone, whom he carried off from the world above. "Hades" later applied to his realm.
Pluto's character was fierce and unyielding, so he was most hated of all gods. He was basically a grim, terrible god, deaf to prayers and unsatisfied by sacrifice. He also possessed a helmet given to him by Cyclopes after their release from Tartarus which rendered him invisible. Hades occasionally lent it out to gods and men.