On June 26, nine days before police shot Alton Sterling outside a convenience store in Baton Rouge, Louisiana, and ten days before police shot Philando Castile on the side of the road in a suburb of St. Paul, Jesse Williams walked onstage at the BET Awards, held at the Microsoft Theater in Los Angeles. The thirty-five-year-old actor was there to accept the Humanitarian Award, an honor previously bestowed upon Muhammad Ali, Al Sharpton, and Denzel Washington. Best known for playing a Casanova doctor on the medical drama Grey's Anatomy, Williams didn't seem to fit the mold. Then he started talking.

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Bowed over a microphone in front of an auditorium filled with thousands of attendees—and seven million viewers watching from home—Williams delivered an indictment of race relations in the United States. He first dedicated the award to social-justice activists and struggling parents, particularly black women. Next, he denounced police brutality against African-Americans. "Yesterday would have been young Tamir Rice's fourteenth birthday," he said, invoking the memory of the boy shot by Cleveland police in 2014, "so I don't want to hear any more about 'how far we've come' when paid public servants can pull a drive-by on a twelve-year-old playing alone in the park in broad daylight, killing him on television and then going home to make a sandwich." After memorializing a handful of other police victims—Rekia Boyd, Eric Garner, Sandra Bland, Darrien Hunt—Williams pivoted to an equally sensitive but often-ignored topic: "We're done watching and waiting," he bellowed, sweat dripping from his brow, "while this invention called 'whiteness' uses and abuses us, burying black people out of sight and out of mind while extracting our culture, our dollars, our entertainment like oil—black gold—ghettoizing and demeaning our creations, then stealing them, gentrifying our genius, and then trying us on like costumes before discarding our bodies like rinds of strange fruit."

"I don't want to hear any more about 'how far we've come' when paid public servants can pull a drive-by on a twelve-year-old playing alone in the park in broad daylight, killing him on television and then going home to make a sandwich."

This was politics as poetry. The crowd, which included many of today's most popular black musicians—Beyoncé, Kendrick Lamar, Young Thug, Nicki Minaj—gave Williams a standing ovation. A video of the denunciation went viral, generating bitter criticism, feverish acclaim, and millions of streams. On Change.org, multiple Jesse Williams petitions appeared, some threatening ABC with a boycott if it didn't fire him from Grey's Anatomy and others imploring the network to stand by him.

One question loomed large: Why had this man, a glorified soap-opera star, stepped into the role of celebrity warrior? We didn't get an immediate answer: Williams went dark on social media for a full ten days and has not addressed the speech since.

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"People respond to white like it's nigger," Williams told me recently at Soho House in Los Angeles. "It's a word you can't say." Although activism is hardly unusual in Hollywood, many stars focus their efforts on causes that emphasize cooperation—saving the environment, say, or ending world hunger. Williams, in contrast, had seized on a problem that implicated large swaths of the entertainment elite. "What I'm talking about is white supremacy. Here. Right now." He wasn't referring to David Duke or Donald Trump—he was calling out the structural racism that governs every funding allocation, every casting decision, and every police interaction in this country. "People feel like they have to push back because I'm criticizing their way of life."

Williams said he'd wanted to address whiteness in the speech in part because he is white. Born in 1981 to a Caucasian mother and an African-American father on the West Side of Chicago, he felt his biracial heritage afforded both advantages and responsibilities. "White privilege is like being Clark Kent and never putting on your Superman suit," he said. "You can do so much! But you're just refusing to. I have white privilege, so I'll use it."

"What I'm talking about is white supremacy. Here. Right now." He wasn't referring to David Duke or Donald Trump—he was calling out the structural racism that governs every funding allocation, every casting decision, and every police interaction in this country.

Over the past four years, Williams has waged an escalating campaign to prick Hollywood's racial conscience. In 2012, he produced "Question Bridge," a traveling art installation that challenges perceptions of black identity through video interviews with black men. In 2013, he wrote an essay for CNN.com calling out director Quentin Tarantino for dehumanizing African-American slaves through violence and slurs in Django Unchained. In 2014, Williams was one of only a handful of celebrities to join the protesters in Ferguson, Missouri, after the police shooting of Michael Brown. Thereafter, he began speaking frequently about police brutality on cable news and on Twitter, offering up equal portions of pith and pique. "Blackness is like the big screen," he tweeted on November 26, 2014, "it adds ten to one hundred pounds, a gun, and a carefully crafted script seen only through the eyes of the white hero." Six months later, he tweeted, "You've watched hulking bullies w/ badges, robes & money brutalize, kill & cage human beings every yr of your entire lives & said nothing." In 2016, Williams produced a documentary for BET about the protesters in Ferguson and elsewhere called Stay Woke: The Black Lives Matter Movement.

When BET's CEO, Debra Lee, introduced Williams at the ceremony, she called him "a modern civil-rights legend in the making." What she didn't know was that Williams had spent the previous twelve weeks in Atlanta, sequestered from the outside world to shoot a remake of Jacob's Ladder, a thriller in which he plays a homeless veteran suffering from addiction and PTSD. "I was literally living in a hotel room by myself with the shades drawn for three months," he said. "I was really, really, really tired."

Williams got the call from BET just two weeks before the ceremony. "I was honored," he told me, "but I was in such a work zone that I didn't spend much time thinking about it." When he was told he would have to give a short acceptance speech, he said he joked, "Oh, you're going to give me a microphone—you probably shouldn't do that." Williams had no special plans for what he would say. "I'm a pretty professional procrastinator, so it was 'I'm going to tackle that on the flight.' " On the five-hour plane ride back to L. A., Williams jotted down some notes on his iPhone. He didn't show his words to anyone before taking the stage.

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Williams expected some kind of reaction—"Every time I go on a news show and do a little one-minute segment, it goes a little viral," he said—but this time he was shocked by the scale. "My phone was exploding every second of every day for the next several weeks." The next morning, Williams flew back to Atlanta, boarded himself up in his hotel room, and transformed back into a homeless vet.

Williams's upbringing primed him for a nuanced perspective on racism. The oldest of three boys, he and his family moved several times during his childhood in a hopeless effort to avoid break-ins. "Chicago was a grimy place in the eighties," Williams told me. "You had crack, heroin. It was very violent." Fistfights at school were a daily ritual. When Williams was in junior high, his family left for a white suburb in southeastern Massachusetts, closer to where his mother had family, crowding into a rented guest house. "They wanted to move before I reached gang-initiation age," he said. At the time, he resented the decision.

While Williams was occasionally teased in Chicago for being light-skinned, "when I went to Massachusetts, I went from 'white boy' to 'nigger' in a week. Literally," he said. "It was coming from my friends' parents, from my teachers—people with actual power to impact my life. Once, my friend's mother was talking about a black person on the news and then looked at me and said, 'Not you, you're not black, you're great.' She meant it sincerely."

Williams won a scholarship to a prep school in Providence, where he headed the Black Student Union and successfully lobbied for a course on African-American literature. The drive to understand his black heritage came from his father, who worked on farmlands in southeastern Georgia. "He worked in tobacco fields and peach fields," said Williams. "White kids would occasionally spit on him as they drove by on their way to school." Williams's father pushed his son to work hard and not depend on school for education. " 'Why would they tell you what is important?' he would say to me. 'It's not in their interest to tell you.' " In addition to his schoolwork, Williams's father would assign "homework," demanding that he write extra papers on topics related to African-American history.

In college—Temple University in Philadelphia—Williams became increasingly interested not just in black history but also in black activism. An African-American Studies major, he led the charge to enhance the department's curriculum through more rigorous African-history courses, and he cofounded a Stokely Carmichael study group. After college, he became a teacher at a troubled Philadelphia high school. "There were a couple loaded guns in my class, police in the hallways," he told me. "Without exaggeration, 30 to 40 percent of the girls had kids or were pregnant." Williams was drawn to the job because high school had been a turning point in his own biography. "It really saved my life in many ways. I felt like I could be of use," he said.

Once, my friend's mother was talking about a black person on the news and then looked at me and said, 'Not you, you are not black, you are gray.' She meant it sincerely.

Throughout his time in Philadelphia, Williams would take the bus up to New York to audition for acting roles. He was once offered a three-year contract to star on a soap opera. "The role was a racist one," said Williams, "a tragic mulatto from the jungle, confused by civilization. I felt like 'What is this, Tarzan?' I wrestled with it for all of five minutes." In 2005, Williams left Philadelphia for New York to move in with a woman he had met at a party, real estate broker Aryn Drake-Lee, who later became his wife. His big break came in 2009, when Shonda Rhimes cast him on Grey's Anatomy for what was at first a recurring role. The following year, he became a regular cast member.

Williams never worried that online protesters might get him fired. "I am interested in twenty other things," he told me. "I don't live and die for this shit." Despite Grey's Anatomy'sdemanding ten-month-a-year filming schedule, Williams has managed to carve out time for several passion projects. In 2011, he started a production company that has been churning out documentaries, including Stay Woke and America Divided, a docuseries about racial inequity that premiered in September on Epix. He sits on the boards of Scholly, an app that helps connect in-need students with scholarship money, and the Advancement Project, a racial-justice think tank. He also handles creative direction for Ebroji, a tech company he founded with his wife in 2015. (The name, a portmanteau of emoji and bro, was his wife's idea.) Its main product is a texting app that allows users to send GIFs inspired by African-American youth culture.

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At the same time, Williams is determined to avoid becoming known for activism alone, which he fears could turn him into "that civil-rights guy who used to work on Grey's Anatomy." The reason he has an impact, he said, is that he's a working actor. "Ali was a great, provocative mind, but it wouldn't have mattered if he was a one-in-fifteen fighter. He had to keep fighting and winning in order to have the megaphone."

Earlier in the summer, Williams turned down an invitation to speak at the DNC. "I am not a politician," he explained. "Anytime I swing that ax, I get flooded with more requests to swing the ax. I am tired, I've got two kids, I work sixteen hours a day on a show, I got seven other jobs. I don't have bandwidth to also be a politician."

Instead, Williams hopes that other celebrities will follow his lead. When I asked what the BET speech had taught him about his own influence, he said, "I think a lot of other people learned something about impact—about the potential that one voice can have." He went on: "Awards shows are typically a ceasefire from politics, and I don't want to pretend we're in a ceasefire."