Re: Serena(8), Henin(7), Venus(6), Martina(5).
Justine will win Wimbledon, so she and Serena's careers will be equally as important. Justine for being the dominant force and Serena for being a pioneering minority in an all white sport by being such a recognizable figure. Yes, I know Althea Gibson and Arthur Ashe were literally the trailblazers, but Serena and Venus could both start a whole generation. Martina was also special in the fact that she was the first player to win Grand Slams with a complete modern game (great all around and with good power for her time).
Tennis's Silver Millennium
Queen Serenity (22)
Princess Garbi (RG '16), Sailor Ana ('08 RG), Sailor Venus (7), Sailor GOATra (2), Sailor Kerber ('16 AO)
Sailor Darth Vika (2), Sailor Sveta (2), Sailor Simona, Sailor Pliskova
Sailor St. Kim (4), Sailor Mahree (2), Sailor Seles (9), Sailor Dokic, Sailor Testud, Sailor Zheng