Robert Pershing Wadlow is the tallest person in history for whom there is irrefutable evidence. Wadlow reached a staggering 8-feet 11.1-inches (2.72-meters) in height and weighed 439-pounds (199-kilograms) at his death at age 22. His great size and his continued growth in adulthood were due to hyperplasia 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. With that said, explaining that he is the fourth person from the left in a photograph probably isn't necessary. Continue reading for more obvious things.