Known for their fearlessness in their duties yet gentle demeanor at home, the Bullmastiff emerges as a robust and muscular guardian with a rich history in Merry Old England, albeit not so merry for poachers. A product of Bulldog and Mastiff lineage, the Bullmastiff, while slightly smaller than its Mastiff counterpart, still commands attention, standing tall at up to 27 inches at the shoulder and weighing between 100 and 130 pounds.