Who suggested the name Pluto for the dwarf planet?

The name Pluto was suggested by an 11-year-old girl named Venetia Phair (then Venetia Burney) of Oxford, England.

After the discovery of the planet was announced in March 1930, her grandfather, Falconer Madan, read the news to her and her mother. Venetia, who had an interest in mythology, proposed the name Pluto—the Roman god of the underworld—for the new celestial body. Madan passed the suggestion to astronomer Herbert Hall Turner, who forwarded it to the Lowell Observatory. The name was ultimately selected by the observatory's astronomers, partly because its first two letters matched the initials of Percival Lowell, the astronomer who had initiated the search for the planet.1