Pluto

Pluto never speaks, and simply makes dog-like sounds, such as howling, barking, and whining noises. Even in his human form, he retains dog-like characteristics, such as continuing to run around on all fours and using his nose to find things. He can turn into his human form upon will, or unintentionally when excited. Pluto does not seem to be overly fond of most people, but listens to Sebastian Michaelis most of the time and is notably envious when Sebastian gives his attention to a cat. He likes Innuko dog treats. Pluto, nicknamed Plu-Plu, is a demon hound that the Phantomhive household picks up in the Black Butler/Kuroshitsuji anime. He is a minor antagonist of the anime. In his human form, Pluto has shoulder-length, silver hair, red eyes and slit pupils, fangs, and black toenails. He is often shown nude in his human form, since he frequently changes back and forth from his human form to his demon hound form. Eventually, he wears a suit. In his demon hound form he becomes a immense and monstrous dog, with white fur.