Another athlete to consider is Bob Mathias. Won his first Decathon in 1948 the summer after his senior year of high school at the age of 18 years old and repeated again in 1952. Won the Sullivan Award in 48' and led Stanford to the Rose Bowl in 1952.
Or how about Jim Thorpe, won both the Decathlon & Pentahlon in 1912 Olympics. Voted the Greatest Athlete of the Twentieth Century.