2. Jim Brown / American Football / Net Worth: $50 Million
Jim Brown was named by Sporting News as the greatest professional football player ever and is widely considered to be among the greatest professional athletes in the history of the United States. He played for the Cleveland Browns throughout his professional career from 1957 to 1965. During that period he was a three-time Pro Bowl MVP (1961, 1962, 1965), helped his team win the NFL Championship in 1964 and was named NFL MVP by various organizations in 1957, 1958, 1963 and 1965, the year of his retirement.