Michael K Williams, who famously played the character Omar Little in TV series The Wire, was found dead in New York on Monday, the New York Police Department said. He was 54.
Lt John Grimpel, a NYPD spokesman, said Williams was found in his Brooklyn apartment after a phone call to emergency operators.
Williams, who received a 2021 Emmy nomination for his performance in HBO's Lovecraft Country, also found fame for his role in the HBO series Boardwalk Empire.
NYPD said there was an "ongoing investigation" into Williams's death and that the New York City medical examiner will determine the cause of death at a later time.
His longtime representative, Marianna Shafran, confirmed the death and said the star's family was grappling with “deep sorrow” at “this insurmountable loss”.
“It is with deep sorrow that the family announces the passing of Emmy-nominated actor Michael Kenneth Williams. They ask for your privacy while grieving this insurmountable loss,” Shafran said.
The news has been met with shock and sadness on social media, as stars and fans of Williams's television shows pay tribute to the star.
Williams's The Wire co-star Isiah Whitlock Jr said in tweet: "Shocked and saddened by the death of Michael K Williams. One of the nicest brothers on the planet with the biggest heart. An amazing actor and soul. May you RIP. God bless."
Wendell Pierce, who also starred in The Wire, said: "The depth of my love for this brother, can only be matched by the depth of my pain learning of his loss. An immensely talented man with the ability to give voice to the human condition portraying the lives of those whose humanity is seldom elevated until he sings their truth.
"If you don’t know, you better ask somebody. His name was Michael K Williams. He shared with me his secret fears then stepped out into his acting with true courage, acting in the face of fear, not in the absence of it. It took me years to learn what Michael had in abundance.
"The Wire brought us together and immortalised Omar and Bunk in that 'scene' on a park bench. But for us we aimed to take that moment in time together and say something about black men. Our struggle with ourselves, internally, and each other. For me and Mike we had nothing but respect," he said.
Actor Edward Norton said he felt "punched in the gut" by the news. "Soul anguished. Getting to work with him was one of the greatest privileges I’ve had in my career. My admiration for his talent was boundless, like so many. If he was in a scene he was the best thing about it. Period," he said in a tweet.
Sharing a video of Williams getting emotional during a panel talking about his time filming Lovecraft Country, former professional basketball player Rex Chapman said: "If you don’t watch anything else today on Michael K Williams passing – please watch these 90 seconds. Life is a team game. We all get by with a little help from our friends. Rest, Michael …"
Preet Bharara, former US attorney for the Southern District of New York, said: "Often on this platform, people are revealed as the awful humans they are. Sometimes on this platform, people are revealed as the wonderful humans they were. RIP Michael K Williams."
Former NYC mayoral candidate Maya Wiley said: "Michael K Williams was not just an outstanding actor. He was committed to criminal justice, building up community and transforming policing. Met him in Brownsville and he was all about it. I couldn’t help but admire him. #RestInJustice and be at peace."
Actress Tika Sumpter, who starred alongside Williams in 2015 film Bessie, said: "God, he was a true gem. I was so lucky to be around him and work with him on Bessie. He was one of the kindest humans in all ways. Being in #MichaelKWilliams presence was a gift. A true gift. Thank you."