Biffy is described as having dark brown hair of an almost chocolate color and kind blue eyes. He has a surprisingly fit and muscular physique. His eyes turn a harsh yellow when he transforms, and his wolf's pelt is roughly the same color as his hair, but with some oxblood red around his chest. According to Alexia, he has darker markings in the fur around his neck that make it appear that he is wearing some sort of neck accessory, perhaps a cravat. Although Biffy is generally displeased with his wolf form, this fact pleases him.