Michael K. Williams, Omar From ‘The Wire,’ Is Dead at 54

When Mr. Williams was cast as Omar in “The Wire,” he returned to Vanderveer Estates to hone his role, drawing on the figures and experiences he had grown up with, he told The Times in 2017.

“The way a lot of us from the neighborhood see it, Mike is like the prophet of the projects,” Darrel Wilds, 50, who grew up with Mr. Williams in Vanderveer, told The Times. “He’s representing the people of this neighborhood to the world.”

Mr. Williams used his celebrity status to advocate several causes, most notably criminal justice reform, both in the United States and in the Bahamas, and he was the A.C.L.U.’s ambassador for ending mass incarceration, appearing in a related ad campaign.

He told The New Yorker in 2014, “Arresting people, or ruining people’s lives for a small, nonviolent charge, like marijuana, drug addiction or mental illness, is not the way to go.” He went on: “Those are health issues, not criminal issues.”

On and off screen, Mr. Williams engaged in discussions about systemic racism amid the Black Lives Matter movement. He plied the legacy of America’s history of racism as he studied for his roles, including as the father of Antron McCray, one of the teenagers wrongfully convicted of raping a woman in Central Park, for Ava DuVernay’s mini-series “When They See Us.” The history was not remote to him: In 1989, when the prosecution of the five men — then teenagers — who became known as the Central Park Five began, Mr. Williams was in his 20s, fearful of what it would mean for him as a Black man living in New York City.

“You, brother, touched many,” Ms. DuVernay wrote in an Instagram post on Monday. “Through your personal interactions big and small, through your community activism, through your struggles, through your triumphs, through your glorious work. You moved many. You moved me.”