William Arnold Pearl was an American professional bodybuilder and athlete. During the 1950s and 60s, he won many titles and awards, including winning the Mr. Universe contest five times, and was named "World's Best-Built Man of the Century". He later became an expert trainer and author on bodybuilding.

Bodybuilding is the practice of progressive resistance exercise to build, control, and develop one's muscles via hypertrophy. An individual who engages in this activity is referred to as a bodybuilder. It is primarily undertaken for aesthetic purposes over functional ones, distinguishing it from similar activities such as powerlifting and calisthenics.