On September 27, the 35-year-old posted an enlightening status on Facebook that detailed her fears for her 18-year-old nephew.
"Today, I asked my 18-year-old nephew (to be clear he's Black) to drive me to my meetings so I can work on my phone #safteyfirst," the tennis phenom wrote. "In the distance, I saw [a] cop on the side of the road. I quickly checked to see if he was obliging by the speed limit. Than (sic) I remembered that horrible video of the woman in the car when a cop shot her boyfriend. All of this went through my mind in a matter of seconds. I even regretted not driving myself. I would never forgive myself if something happened to my nephew. He's so innocent. So were all 'the others.'"
"But I realized we must stride on — for it's not how far we have come but how much further still we have to go," she wrote on Facebook. "I had to take a look at me. What about my nephews? What if I have a son and what about my daughters? As Dr. Martin Luther King said "There comes a time when silence is betrayal."
She concluded the eye-opening post with four simple words: "I won't be silent."
Williams public commitment to speaking up is new. However, this isn't the first time she's championed important causes. In fact, there are seven other times she's lent her voice to fighting injustice.
She raised a hefty sum for an organization that fights mass incarceration.
Williams has frequently thrown her name behind important causes, like the Equal Justice Initiative, a non-profit organization that offers wrongfully-convicted prisoners pro-bono attorneys. She's raised $100,000 for EJI, according to their executive director Bryan Stevenson.
"It's been huge," Stevenson told Sports Illustrated after they named Williams sportsperson of the year. "It's so rare when athletes at the top of their game are willing to embrace a set of issues that, for a lot of people, are edgier. This is not aid to orphans. These are questions of racial bias and discrimination, mass incarceration, excessive punishment, abuse of the mentally ill. You don't change the world by doing what's comfortable or convenient. You have to be willing to do uncomfortable things."
She refused to play the Indian Wells tournament for 14 years after a racist incident.
Serena Williams and her sister, Venus Williams, did not play in the Indian Wells tournament from 2001 to 2015. Though they're arguably tennis' biggest draws, the dynamic duo enacted a self-imposed Indian Wells exile after encountering racism.
The audience booed and hurled racist slurs at the Williams sisters and their father after Venus withdrew from a match four minutes before it began. Serena Williams recounted the incident in her 2009 memoir "On the Line."
"I looked up and all I could see was a sea of rich people — mostly older, mostly white —standing and booing lustily, like some kind of genteel lynch mob," she wrote. "I don't mean to use such inflammatory language to describe the scene, but that's really how it seemed from where I was down on the court. Like these people were gonna come looking for me after the match. There was no mistaking that all of this was meant for me. I heard the word n***er a couple times, and I knew. I couldn't believe it."
Serena changed her mind about playing Indian Wells after reading Nelson Mandela's autobiography "Long Walk to Freedom." "That’s when I realized I had to go back," she told Vogue in March 2015. "I always talk about forgiveness, but I needed to actually show it. It was time to move on."
Stevenson considers Williams' Indian Wells exile "an act of courage." "She was standing when a lot of her contemporaries remain seated, speaking up when others are being quiet," he told Sports Illustrated. "That's an act of hope and an act of courage, but it's also an act of change."
She let the world know tennis has a racial wage gap.
Williams is now tennis' highest-paid female player, according to Forbes, but it hasn't always been that way. Until June, Maria Sharapova had been the highest-paid female tennis player, though she'd lost to Williams 18 consecutive times. In fact, Sharapova hasn't beaten Williams since 2004.
This disparity exposes a racial wage gap in tennis. As The Atlantic points out, Williams is the biggest draw in tennis. The women's finals in the US Open have higher television and attendance ratings than the men's finals. Yet, Williams still earned $40 million less than Roger Federer, whose ranked fourth while she's ranked first.
Forbes attributed this gap to corporations' willingness to market men and white women while failing to see Williams' marketability. "Does ethnicity and 'corporate bias' play a partial role in explaining the endorsement gap?" Forbes asked in the article. "In all likelihood, yes."
In an interview with The New York Times, Williams acknowledged the racial wage gap, but also showed that it doesn't phase her. "If they want to market someone who is white and blond, that's their choice," she said in August 2015. "I have a lot of partners who are very happy to work with me."
She vocalized her support for the Black Lives Matter movement.
Outside of her viral Facebook post, Williams has expressed her support for Black Lives Matter in the past. In an October 2015 essay for Wired, the tennis champ encouraged organizers and activists to keep pushing forward.
"To those of you involved in equality movements like Black Lives Matter I say this: Keep it up," she wrote. "Don't let those trolls stop you." In a Q&A at the University of Pennsylvania in November 2015, Williams said Black activists have inspired her to be more vocal about social injustice.
"I've been a little more vocal, but I want to do more," she said. "I want to help everyone to see the so-called light. But there are a lot of other athletes, actors, politicians who are speaking out — of all colors, by the way. They're not sitting back. They're calling for justice straight away. It makes me look at myself and say, like, 'What am I doing?' I have a platform. I can speak out, too. If one person hears me, maybe that person can speak out and help. I embrace that. I'm willing and happy to be part of this new movement."
She raised the stakes at Wimbledon by calling out cops who've killed unarmed citizens.
Williams spoke out against police brutality after shootings in Baton Rouge, Louisiana and Falcon Heights, Minnesota in July. She tweeted about the police shooting death of Philando Castile after defeating Elena Vesnina in a Wimbledon semi-finals match.
"In London I have to wake up to this," she tweeted. "He was Black. Shot four times? When will something be done — no REALLY be done?!?!"
She expanded on those comments in an interview after Wimbledon with freelance journalist Ben Rothenberg.
"I feel anyone in my color in particular is of concern. I do have nephews that I'm thinking, do I have to call them and tell them, 'Don't go outside. If you get in your car, it might be the last time I see you.' That is something that I think is of great concern, because it will be devastating. They're very good kids. I don't think that the answer is to continue to shoot our young black men in the United States. It's just unfortunate. Or just Black people in general."
She called out a sexist tennis official — and forced him to resign.
Raymond Moore, CEO of the Indian Wells tournament, made a grave mistake when he dismissed Williams and fellow female tennis players on March 20.
"If I was a lady player, I'd go down every night on my knees and thank God that Roger Federer and Rafa Nadal were born, because they've carried this sport," Moore told reporters, according to ESPN.
Williams quickly retorted after her match. "We, as women, have come a long way," she told reporters at a press conference. "We shouldn't have to drop to our knees at any point." She then highlighted how she and Venus were responsible for the 2015 women's US Open finals selling out before the men's final.
"I'm sorry, did Roger play in that final, or Rafa or any man play in that final that was sold out before the men's final?" Williams asked. "I think not."
The next day, Moore stepped down as CEO and director of Indian Wells.
She stood up for all women by chasing down a car thief.
In November, Williams recounted a terrifying experience at a restaurant. She, Venus, and fellow tennis player Caroline Wozniacki were eating dinner when a thief stole Williams' phone. Instead of letting the thief escape, Williams chased him down.
"Not thinking I reacted (hence the superwoman photo) I jumped up, weaved my way in and out of the cozy restaurant (leaping over a chair or two) and chased him down," she wrote in a viral Facebook post. "He began to run but I was too fast. (Those sprints came in handy) I was upon him in a flash!"
She retrieved her phone — and probably scared the thief half-to-death. Williams then decided to write about the experience to encourage women to "step up to any challenge."
"Always listen to your superhero inner voice," she wrote. Then, in words that seem to echo what she's done in her career, Williams wrote, "Fight for what's right. Stand for what you believe in! Be a superhero!"
That superhero confidence surely fuels Williams, who told reporter Mark Masters that she's not one of the best female athletes of all time. She's one of the greatest athletes ever.
Indeed — and this list of what she's done outside of the court proves it.