Playful and clownish, the Bull Terrier is best described as a three year-old child in a dog suit. Given his muscular build, the Bull Terrier can appear unapproachable, but he is an exceedingly friendly dog, with a sweet and fun-loving disposition and popular in the obedience, agility and show rings. The Bull Terrier can be all white (markings on the head are permissible) or colored.