He was just 54 years old.
Michael, who also starred in Boardwalk Empire, and more recently, the HBO series Lovecraft Country, was found dead in his Brooklyn apartment by his nephew.
While his death is an unexpected tragedy, fans of the Emmy-nominated actor took to social media to share their memories — but what happened?
Michael K. Williams' cause of death has yet to be reported.
No official cause of death has been reported but according to The New York Post, drug paraphernalia was found in his apartment, which could suggest a drug overdose.
"No foul play indicated," a police source told the outlet. "No forced entry, the apartment was in order."
Following the reports of his death, many took to social media to remember the talented actor.
"Michael K Williams, in addition to being one of the most talented actors around, was also one of the kindest, sweetest, most gentle souls I’ve ever met. This is heartbreaking. My thoughts are with all those who loved him," director James Gunn tweeted.
TV host and actress Aisha Tyler also shared her condolences, writing, "Michael K. Williams was a beautiful, passionate, expansive soul. I felt so lucky to have known him, and we were all so fortunate to have enjoyed his incredible talent. He burned so very bright."
Michael K. Williams' net worth was estimated at $5 million at the time of his death.
Michael got his big break in acting after being discovered by Tupac Shakur and cast as High Top in the 1996 film Bullet. However, it wasn't until 2002 that he became a household name thanks to his role as drug dealer Omar Little on The Wire, regularly considered one of the best television shows of all time.
Even President Barack Obama called Omar his favorite TV character. "That's not an endorsement. He's not my favorite person, but he's a fascinating character. ... He's the toughest, baddest guy on the show," he said in 2008.
Other major works on Michael's IMDb page include Boardwalk Empire, Assasin's Creed, Lovecraft Country. His net worth at the time of his death was estimated at $5 million.
While Michael's death is an unspeakable tragedy, fans can expect more of his work to be released following his death. He has two movies (Surrounded and 892) with expected posthumous release dates. In one of his last Instagram posts, Michael revealed that he was excited to start working with director George Tillman on a George Forman biopic.
Our thoughts are with Michael's family and friends during this difficult time.