Robert Pershing Wadlow (February 22, 1918 – July 15, 1940) was the tallest person in history for whom there is irrefutable evidence. Wadlow is sometimes known as the Alton Giant or Giant of Illinois because he was born and grew up in Alton, Illinois.
Wadlow reached 8 ft 11.1 in (2.720 m) in height and weighed 439 lb (199 kg) at his death at age 22. His great size and his continued growth in adulthood was due tohypertrophy 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.