A Bulldog, also known as British Bulldog or English Bulldog, is a breed of dog which traces its ancestry to England. 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 blubber on a bulldog's brow, followed by round, black, eyes that are far apart, a short muzzle, drooping lips, and the pointy teeth.

In the US, the size of a typical mature male is about 50 pounds and that for mature females is about 40 pounds. In the [United Kingdom], the breed standard is 55 pounds for a male and 50 pounds for a female, though it is not uncommon for males to be 60 pounds.

While some canine breeds require their tails to be cut or "cropped" soon after birth, bulldogs are one of very few breeds whose tail is naturally short and curled. A longer or "gay" tail is a serious fault in a show bulldog.