Bill is a large and heavyset man, though by 1899 he appears to be somewhat fat. He has brown hair and a bushy beard. Though not bald, his hair is clearly receding and he also seems to be missing some teeth. His usual attire consisted of grey trousers, boots and either a plain white or a checkered shirt, sometimes accompanied by a long, brown leather jacket and/or his hat which he wears pinned on one side. For the Saint Denis bank robbery, Bill wears a square-patterned grey suit and, in Guarma, his suit jacket is absent and he wears a white shirt with braces, with the same grey-patterned trousers.

Bill's primary weapon is a custom Bolt Action Rifle. However, he also holsters a custom Schofield Revolver with a black steel frame, although it is rarely used.