5. Mastiff

If you measure dogs purely by mass, the English Mastiff often tops the list. Males easily exceed 200 pounds, possessing heavy bones, massive heads, and a deeply wrinkled forehead that gives them a constantly worried expression.

The Mastiff is a dog of quiet dignity. They do not bark excessively and rarely show unwarranted aggression. Instead, they protect their home simply by existing; their sheer size deters intruders. With their family, they are endlessly loving and gentle giant dog breeds. They require moderate daily walks to keep their joints healthy, but their favorite activity is napping on the most comfortable mattress they can find.