Purpose
Bull Terriers arose from a family called "bull and terrier" dogs during the 19th century.  Bull terriers were bred for companionship and the sport of conformation, not for fighting.  It is true that during the creation of this breed, the sport of dog fighting was prevalent, but the creator of this breed created bull terriers for the purpose of selling a dog to the general public that was beautiful to the eye.  For the past 136 years, this breed sole purpose is that of companionship.

Creation
The modern bull terrier is believed to be created with the now extinct English White Terrier, the Bulldog, the Dalmatian, several terrier crosses, and some believe the Spanish  Pointer, Greyhound, and Foxhound.  There is even some evidence to suggest that the Borzoi and Collie were used to help elongate the head.

Ears
One interesting fact about the breed is the development of the natural tulip ear shape. In 1895, King Edward VII expressed This opinion to stop ear cropping to the Kennel Club, in turn they declared the ban of ear cropping which did set the breed back several years.  This forced English Bull Terrier fanciers to redesign the ear.  he person most credited with the development of the tulip ear is Harry Monk.  The United States did not accept the change as quickly.  It wasn't until 1956 until the standard was finally rewritten calling for an erect ear.  The standard had called for a cropped ear up until the early 30s. 

Head
The original designer of the down faced head is Harry Monk.  The dog who created the foundation of the modern bull terrier head is Bloomsbury Charlwood, who is noted to have possessed an excellent head and ear placement. The person responsible for the carrying on this head and improving the egg shaped face is Billie Tuck. Breeders over the years have carried on the tradition to improve the Bull Terrier head and strive to come as close to the standard as possible.

Color
Another interesting fact of Bull Terrier history is the development of color in Bull Terriers.  James Hinks, the one of the founding fathers of Bull Terriers, bred a strain of all white bull terrier dogs. With popularity, only white bull terriers were shown.  This is where the term "White Cavalier" originated.  The all white dogs were seen with occasional patches of color found mostly on the head.  During the redevelopment of the breed after the ear cropping ban, and the movement to the downward head we now see in today's Bull Terriers, the acceptance of color on the head arrived in the show ring.  And due to a few determined breeders, the dogs were outcrossed to the older styled colored terriers.  The man who is known for the development and acceptance of colored bull terriers in the ring is Ted Lyon, whose preferred color was brindle.  Today there is no such dog of a pure white Bull Terrier.  All Bull terriers, including those who appear all white in color are colored bull terriers.  The white bull terriers of today are a result of a white masking factor that masks the color of the dog.  Even today, with all things being equal the preferred color for colored Bull Terriers is brindle, due to the fact that brindle can be easily lost.