We call ours a Boxer Mastiff but I have not been able to find any regular cross between the two that would have a standard name. Our dog has a mother who was a pure boxer and a father who was a pure bull mastiff. He inherited the beautiful fawn coloring, size, and strength from his father, but the leanness, agility, speed, and playfulness of his mother. His muzzle is more elongated than a boxer's would be so he doesn't suffer from breathing problems and he is so long and lean that he is not the stocky build of a bull mastiff. Depending on your frame of mind, he can be mistaken for a very very large boxer or a young bull mastiff as he picked up the good looks of both. I personally think he is such a handsome dog and the best of both worlds, that this should be recognized as a new breed.