William Henry Johnson was born to a very poor African-American family. His parents were William and Mahalia Johnson, former slaves. As he grew his body developed normally but his head remained small. His tapering cranium and heavy jaw made him attractive to agents from van Emburgh's Circus in Somerville, New Jersey. His unusual appearance caused many to believe that he was a "pinhead", or microcephalic. Microcephalics are characterized by a small, tapering cranium and impaired mental faculty. It is arguable, however, that William Henry was not mentally deficient.
William Henry's parents agreed to allow the circus to display him in return for money. He was billed as a missing link supposedly caught in Africa and displayed in a cage. He was a popular draw and his success led young William Henry's agent to show his charge to P.T. Barnum.
Barnum purchased the right to display William Henry Johnson from the circus and gave him a new look. A furry suit was made to fit him, and his hair was shaped to a tiny point that further accented his sloping brow. Finally, he was given the name, "Zip the Pinhead," the "What-Is-It?"