The Bullmastiff is a powerful dog, which was originally a cross between the English Mastiff and the Old English Bulldog. Originally bred to find and immobilize poachers, the breed has proven popular as a family pet.

A Bullmastiff should be fearless and confident, yet docile. A Bullmastiff is courageous, extremely loyal to its family, calm, and loving. It has a very strong protective instinct and will defend against any threat to its owners, as well as any threat to its territory. Bullmastiffs become intensely attached to their families. Their protective instinct combined with their great size and natural wariness of strangers means that early socialization and obedience training is essential. A male Bullmastiff should not live with another male dog. The Bullmastiff can get along extremely well with children provided the dog has been properly trained and socialized. Parental supervision must be maintained when they are with children; they may knock smaller children down accidentally because of their large size. A Bullmastiff, because of its history, is a very independent dog, and likes to make its own decision. However, with good training, a Bullmastiff will look to its owner for "permission" to act on its instincts. Obedience training with all members of the family will teach the dog to look to them before taking action.