A Bulldog, also known as British Bulldog or English Bulldog, is a breed of dog which traces its ancestry to the British Isles. It should not be confused with other varieties such as the American Bulldog or the French Bulldog, which have a similar appearance. The bulldog is a breed with characteristically thick shoulders and a matching head. There are generally thick folds of skin on a bulldog's brow, followed by round, black, wide-set eyes, a short muzzle with characteristic folds called "rope" above the nose, with hanging skin under the neck, drooping lips, and pointed teeth.

Despite their famous "sourpuss" expression, bulldogs are generally docile although can prove to be very fast movers over a short distance. They are friendly and gregarious but occasionally willful. The phrase "stubborn as a bulldog" is loosely rooted in fact.