Robert Pershing Wadlow (February 22, 1918 – July 15, 1940) is the tallest person in history for whom there is irrefutable evidence. Wadlow is sometimes known as the Alton Giant or Giant of Illinois because of his upbringing in Alton, Illinois.
Wadlow reached 8 ft 11.1 in (2.72 m) in height and weighed 485 lb (220 kg) at his death at age 22. His great size and his continued growth in adulthood was due to hypertrophy of his pituitary gland which results in an abnormally high level of human growth hormone. He showed no indication of an end to his growth even at the time of his death.
Wadlow's size began to take its toll: he required leg braces to walk, and had little feeling in his legs and feet. Despite these difficulties, Wadlow was never confined to a wheelchair. On June 27, 1940 (eighteen days before his death), he was measured at 8 ft 11.1 in (2.72 m) by doctors C. M. Charles and Cyril MacBryde of Washington University School of Medicine in St. Louis.