Serena Williams is the most decorated female tennis player of all time. She's been ranked #1 by the Women's Tennis Association countless times since 2002, and no one holds more Grand Slam titles--not just as a single's player, but also, with her sister Venus, in women's doubles. Find out all about this powerhouse player and her dozens of amazing victories--and decide for yourself: is Serena the G.O.A.T. of tennis?