Diaval was a character in Disney's Maleficient. He was an update of the raven, Diablo, that appeared in the animated movie Sleeping Beauty. In Maleficient, Diaval pledged to be Maleficient's servant after she saved his life. Maleficient transformed Diaval into various creatures, including a human, wolf, horse and dragon, but she used him mostly to be her wings, since she no longer had hers.
Diaval is an invented name. It has never appeared in SSA's name database. It's a little too out there for a person, but I think it would be an awesome name for a pet, especially a black one.