1. English Mastiff: The largest of the mastiff breeds, known for its massive size and gentle nature.
2. Bullmastiff: A cross between the Bulldog and the English Mastiff, known for its strength and loyalty.
3. Neapolitan Mastiff: A massive breed originating in Italy, known for its wrinkled skin and droopy jowls.
4. French Mastiff: A smaller breed than the English Mastiff, known for its athletic build and intelligence.
5. Tibetan Mastiff: An ancient breed originating from the Himalayas, known for its thick coat and independent nature.
6. Spanish Mastiff: A large and powerful breed originating from Spain, known for its guarding instincts and loyalty.
While these are the six main breeds, there are also various mixed breeds and lesser-known mastiff-type dogs, often originating from specific regions or historical lines.