Serena, on her own and in cooperation with her sister Venus, has been a major force for equal pay and recognition for women within tennis and sports in general. Through her efforts, women tennis players have begun to receive pay equal to their male counterparts in many high-profile tournaments, beginning with Williams’ own 2007 win at Wimbledon. Williams has championed equality even when she’s faced criticism for her work.

“The day I stop fighting for equality and for people that look like you and me will be the day I’m in my grave,” Williams said in 2019 in response to comments by tennis legend Billie Jean King that implied that Serena could win more titles if she focused less on other activities. King later clarified that she wasn’t trying to imply that Williams stop advocating for women or other issues.

I would never ask anyone to stop fighting for equality. In everything she does, Serena shines a light on what all of us must fight for in order to achieve equality for all.

— Billie Jean King (@BillieJeanKing) July 13, 2019

Long before it was common, Williams has been using her celebrity to highlight police violence against Black people. In 2015, Williams went on Twitter to acknowledge the killing of Chrisitan Taylor, an unarmed 19-year-old who was shot and killed by a police trainee after Taylor drove a car through the window of a car dealership in Arlington, Texas.

In 2016, she similarly spoke out via Facebook after the killings of Philando Castile and Alton Sterling.  And in 2020, Williams posted about the murder of George Floyd days after he was killed, tweeting “with a heavy heart” and supporting protests that rose around the country. “Now, we as Black people have a voice,” Williams said later that year, noting how technology was helping to bring such killings into the public consciousness.

In addition to using her platform to highlight instances of police brutality, Williams has also supported fellow athletes who have engaged in protests. In 2018, as Colin Kaepernick and Eric Reid were facing their first year of being blackballed by the NFL, Williams expressed vocal support for the players and their protests. “I think every athlete, every human, and definitely every African-American should be completely grateful and honored how Colin and Eric are doing so much more for the greater good,” she said during the 2018 U.S. Open.

William also applauded Nike for featuring Kaepernick in a prominent campaign that highlighted his activism. Williams herself then became the next athlete featured in the Nike campaign. In 2020, Williams’ husband, Reddit Co-founder Alexis Ohanian, donated $1 million to Kaepernick’s Know Your Rights Camp Legal Defense Initiative.

In their hometown of Compton, Calif., Serena and Venus founded the Yetunde Price Resource Center, named in honor of their murdered sister, to combat community violence. She has also supported and promoted a variety of national causes, such as the Equal Justice Initiative. Internationally, Serena has partnered with Build Africa to build schools in Kenya, Uganda and Zimbabwe, and worked with Helping Hands Jamaica Foundation to build the Marsh Elementary School in that country as well.

Williams has long been a fashion icon and iconoclast within the tennis world, dating back to the much-talked-about beads that she and Venus wore in their braided hair as teenagers in the 1990s. Serena has continued to turn heads — and deflect criticism against her style and her body — for her provocative outfits, such as the catsuits she wore at the U.S. and French Opens — such outfits were even banned at the French tournament. Like many athletes, Serena has ventured into creating her own fashion lines, with her ventures being extremely successful. Through her apparel, Williams has promoted not only style but also body positivity, producing her clothes to fit a variety of shapes and sizes.

In 2017, Williams added mother to her many roles, giving birth to daughter Alexis Olympia Ohanian Jr. via an emergency c-section. The experience was harrowing for Williams, who experienced potentially fatal complications as a result of her pregnancy and delivery and had to fight to receive proper medical care.

Williams shared her experience publicly to advocate for other Black women who systematically receive lower-quality care during pregnancy and birth, and who are three times as likely as white women to die during childbirth. By recounting her experiences, which also included postpartum depression, Williams greatly increased awareness of the challenges that women in general, and Black women in particular, face surrounding pregnancy and childbirth.

Though Williams is only 40, she has spent most of her life playing professional tennis and has thus had the opportunity to play against a new generation of Black women in tennis who she helped inspire to enter the game. In 2020, for example, the U.S. Open featured a record 12 Black American women, and this year’s tournament has similarly featured a high number of Black women, as well. If Williams does indeed retire after this year’s U.S. Open, she will leave the game to rising stars such as Naomi Osaka, Sloane Stephens, Coco Gauff and Madison Keys, among others.

While Williams may be hanging up her racket, she will have even more time to engage in the types of activism for which she has become well-known. And in doing so, she will only add to her already unmatched legacy, on and off the court.