Baskerville

Baskerville（バスカヴィル, Basukaviru), also known as the Black Dog (ブラック・ドッグ, Burakku Doggu), is one of Alucard's familiars in the Hellsing series. Its form varies, but it usually appears as a large dog with shaggy black fur, multiple red eyes, and a large, fangy mouth.

Baskerville appears to be one of Alucard's favorite familliars, since he tends to use it against opponents he considers challenging.

The name "Baskerville" is a reference to the Sir Arthur Conan Doyle novel, "The Hound of the Baskervilles". Its name was revealed in Volume 9, when Alucard summons it against Walter.

It seems to be able to absorb powers for itself as in the case with Luke Valentine, as Alucard states that it wasn't a complete waste to feed him to his dog, after observing it's speed and movements similar to Valentine's.

Baskerville meets its apparent end by being cut in half by Walter. Luke emerges from its remains shortly before being invaded by Walter's wires to use Baskerville as a puppet against Alucard. In the anime, after Alucard is killed by Incognito, he returns from hell in the form of Baskerville.