When you think about women's tennis, it's hard not to go right to the Williams sisters.
Since Venus debuted on the tour in 1994, it was clear that she was going to be a force for a very long time. Serena came soon after, making her professional debut in 1995.
Serena was the first of the two sisters to win a Grand Slam title, defeating Martina Hingis in the 1999 US Open final. It didn't take long for Venus to make her mark, though. In 2000, she emerged as the winner at both the US Open and Wimbledon.
The 2001 season was, however, a memorable year for both of them. At the US Open, Venus and Serena met in the final, becoming the first sisters to face one another in a Grand Slam final since Maud Watson defeated Lillian Watson in the 1884 Wimbledon final. Venus won the match in straight sets, and didn't lose a single set on her way to winning the championship. It was a match that the two still take a lot of pride in, and it will be remembered forever.
Since making their singles debuts, the Williams sisters have racked up a total of 30 Grand Slam titles. Twenty-three of those were won by Serena, who is just one title away from tying Margaret Court's record of 24 majors.
The two have also had an amazing career in doubles, as they have won 14 Grand Slams as a team. We haven't seen them play together in a while, but that doesn't change the fact that they were the most dominant doubles team in women's tennis history.