Robert Pershing Wadlow (February 22, 1918 – July 15, 1940) was a man who, to this day, is the tallest person in medical 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 feet 11.1 inches (2.72 m)[1][2] in height and weighed 490 pounds (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.