Secretariat was the greatest racehorse who ever lived. He won the Triple Crown back in '73, winning the last event (The Belmont Stakes) by 31 lengths, setting a course record that still stands today. Also known as "Big Red", he had more heart than any other athlete I've ever seen. Sports Illustrated magazine ran a list of the top 100 athletes of the 20th century, and Secretariat was the only non-human to make the list (I think he placed #31).