A mastiff is a type of large dog often used as guard dogs. Mastiff breeds include:
- English Mastiff, or mastiff, the largest breed of dog in the world, bred as a Roman war dog.
- Alpine Mastiff, an extinct breed originating in Switzerland
- American Mastiff, a breed of dog originating in the United States
- Anatolian Mastiff, an ancient breed of dog originating in Turkey (when it was part of the Persian Empire in 485 AD)—see Anatolian Shepherd Dog
- Argentinian Mastiff, or Dogo Argentino a mastiff developed in Argentina for large game-hunting
- Bordeaux Mastiff or French Mastiff, two alternative names for the Dogue de Bordeaux, one of the most ancient French breeds
- Brazilian Mastiff, another name for the Fila Brasileiro a breed of dog originating in Brazil
- Bullmastiff, said to be a cross between the English Mastiff and the Bulldog
- Bully Kutta, Pakistani Bully Kutta
- Cane Corso Mastiff, or Italian Mastiff, breed which originated in Italy and best known as the Cane Corso
- Cuban Mastiff, an extinct breed resembling a Bullmastiff, originating in Cuba
- German Mastiff, better known as Great Dane, a breed of dog originating in Germany
- Japanese Mastiff, also known as Tosa Inu, bred as Japanese fighting dogs
- Korean Mastiff, also known as Dosa Gae, a breed of Korea bred from Tosa Inu and European breeds
- Neapolitan Mastiff, an ancient breed of dog originating in Italy
- Gran Mastín de Borínquen, also known as the Puerto Rican Mastiff, a breed of dog originating in Puerto Rico
- Perro de Presa Canario, a breed originating in the Canary Islands of Spain
- Pyrenean Mastiff, a guardian breed of the Spanish Pyrenees
- South African Mastiff, also known as Boerboel, a breed of dog originating in South Africa
- Spanish Mastiff, an ancient breed of dog originating in Spain
- Tibetan Mastiff, an ancient breed of dog originating in Tibet
- Roman Rottweiler, used by the romans to herd and guard cattle
Mastiff may also refer to:
- Tadiran Mastiff, a battlefield unmanned aerial vehicle (UAV) built by Tadiran Electronic Industries
- Mastiff (company), video game company
- Mastiff, British Army designation for the Cougar (vehicle) armoured fighting vehicle, with extra armour, including cage armour