The Bullmastiff was developed in Britain and recognised officially in 1924. Sixty percent of its background comes from the Mastiff and the other forty comes from the Bulldog. The dog's purpose was to serve as the night watch for gamekeepers. By the end of the 19th century, poaching of game on large estates had become common and poachers would rather kill the gamekeeper than face the death penalty themselves. The Bullmastiff was quick and agile; it was courageous enough to attack on command, hold the perpetrator, and yet not maul him. The Bullmastiff also worked as an army dog and a police dog, as well as family protector.

Appearance
The Bullmastiff is 60% Mastiff and 40% Bulldog. It is powerfully built and symmetrical, showing great strength, but not cumbersome; it is sound and active.

Character
The Bullmastiff's personality is a well-rounded and robust one. It is fearless, obedient, loyal and affectionate and makes a good family protector. The breed also does well in obedience.
 

Temperament
The Bullmastiff is courageous, loyal, calm, and loving with those it knows. It has a very strong protective instinct and will defend its people against anything it perceives as a threat. However, the Bullmastiff does not normally attack to protect. Instead, it simply knocks the intruder over with its massive size and pins them to the ground, or, will simply stand in front of the stranger/intruder and refuse to let them pass. Bullmastiffs become intensely attached to their families and do best when they can live inside with their people. Their protective instinct combined with their great size and natural wariness of strangers means that early socialization is a must. The Bullmastiff may or may not get along well with other dogs. Often, male Bullmastiffs do not tolerate other males, regardless of breed. Occasionally, females are also intolerant of other females. The Bullmastiff, in general, loves children and is very patient with them. Parental supervision should be maintained when they are with children because these dogs are so big that they can easily cause accidental injuries while playing with them.

Exercise/Training
The Bullmastiff is a big dog and needs daily exercise to stay in shape. Its needs are moderate, however, and can be met with walks on leash and short romps. The Bullmastiff does not do well in hot, humid weather and generally should be kept as an indoor dog. It needs a soft bed and plenty of room to stretch out.

Color
Any shade of brindle, fawn, or red is allowed at the Bullmastiff as long as the color is pure and clear. In the United States, however, there is no mention in the standard of the color being "pure and clear". The fawn is a light tan or blond color, while the red is a richer, red-brown. This can range from a deep red to a light red merging with the fawn sometimes described as a red-fawn. A slight white marking on the chest of the Bullmastiff is permissible, but other white markings are undesirable. A black muzzle is essential, toning off towards the eyes, with dark markings around eyes contributing to the expression.

Grooming
The coat of the Bullmastiff needs minimal care. A good nutrition and regular brushing keeps the proper coat shine and the skin healthy. Bathing doesn’t harm the coat of the Bullmastiff as long as you use a good quality shampoo that doesn't dry the skin and coat and is formulated for a canine coat. The ears of the Bullmastiff should be kept clean and regularly inspected as well.

Any breed described as "good with children", the dog must be accustomed to children. Any dog that is not well socialized with children will not behave predictably around them. As with all dogs, they should never be left alone with young children.