The Mastiff, also called the English Mastiff, is a large breed of dog. They have a rectangular body, thick muscles and a massive head with a wrinkled forehead. They stand from 27.5 inches (70 cm) to 30 inches (76 cm) at the shoulder and typically weigh between 120 pounds (54 kg) and 230 pounds (100 kg). The Mastiff is one of the largest breeds of dogs who can outweigh many full-grown men. They can be gentle with family members but are also excellent guard dogs.