The Hound was the real victim

Even though the story is called the Hound of the Baskervilles and the Hound is the villain or one of the villians in the story. It is in fact the real victim. Stapleton purchased the most vicious and large Hound he could find, probably on the black market. He beat, brutalised and starve the animal to give the beast that back from the dead look. The animal didn't know any better. Stapleton used the hound's grisly appereance to shock Sir Charles into having a fatal heart attack. Then using Sir Henry's old boot to give the hound the scent when pursing Sir Henry across the moor.

The hound is put out of it's misery by Holmes and Watson shooting the animal. The poor animal never knew love and compassion from it's owners. It was just an innocent animal that was mutilated and manipulated by it's cruel master. Stapleton is the true Hound of the Baskervilles.