Bullmastiff

The Bullmastiff was created by English gamekeepers to catch poachers. They needed a dog big enough to knock a man down and hold him, but controlled enough not to maul him. The result: 60% Mastiff, 40% Bulldog, 100% nighttime security. They're called the 'gamekeeper's night dog' for a reason. Quiet, powerful, and perfectly content to spend all day lying around until someone crosses a boundary.

Giant breed, short lifespan. That's the trade-off. Bullmastiffs average 7-9 years, and the final years can be expensive. Hip and elbow issues are common. They drool — not as much as some mastiff types, but it's there. They don't need much exercise (moderate walks are fine), but they do need space because they're huge. Surprisingly good apartment dogs temperament-wise, but physically you need room. Training must happen early; a 130-pound dog that pulls on leash is a liability.