Robert Wadlow, World's Tallest Man

Robert Pershing Wadlow, also known as the Alton Giant and the Giant of Illinois, was an American man who was the tallest person in recorded history for whom there is irrefutable evidence. He was born and raised in Alton, Illinois, a small city near St. Louis, Missouri.Wadlow's height was 8 ft 11.1 in while his weight reached 439 lb at his death at age 22. His great size and his continued growth in adulthood were due to hypertrophy of his pituitary gland, which results in an abnormally high level of human growth hormone.

Source: Wikipedia