World Tallest Man living and dead:
Found in United States
Name: Robert Wadlow
Metric & Imperial: 272 cm , 8 ft 11.5 in
Note: Confirmed tallest male and person by Guinness World Records.
Life Span: 1918–1940
Robert Pershing Wadlow (February 22, 1918 – July 15, 1940) was a man who 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 222 kg (490 lb) 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.