No. 3: Venus Williams

No. 3: Venus Williams
Tennis
Income: $15.4 million
Age: 30

Williams pitches for Oreo, Powerade, Tide and Wilson, among others. She co-authored the book, "Come to Win," released in July, which looks at successful people who played sports as kids, including Richard Branson, Bill Clinton, Jack Welch and Meg Whitman.