Pluto was the god of the underworld in Roman mythology. He abducted Proserpina (Gr. Persephone), and her mother Ceres (Gr. Demeter) caused winter in her grief. In later times he was largely seen as synonymous with the Greek god of the underworld Hades.
The planet Pluto is -in part- named after him.
Pluto should not be confused with the Greek god Ploutos, the god of riches.