Caroline Wozniacki

 Earnings: $13.7 million

2011 ranking: 2

2011 earning: $12.5 million

Wozniacki ranked No. 1 in the world at the end of each of the past two years, despite never winning a Major tournament. She earns more than $10 million annually from appearances and sponsors like Adidas, Yonex, Proactiv, Rolex and Sony Ericsson. She is releasing her own line of underwear in September.