Michael K. Williams

He was given one of his first acting roles after being discovered by Tupac Shakur and was cast as High Top, the brother and henchman to Shakur's drug kingpin Tank, in the 1996 film Bullet.

Williams gained recognition as an actor for his portrayal of Omar Little in The Wire, which began filming in 2002. The character was based on Donnie Andrews, as well as other crime figures in Baltimore. Williams received the part after only a single audition. He was initially told that the character was slated to appear in just seven episodes of the first season and feared that the character would be killed before the end of the season. However, creator David Simon stated that they always planned to keep the character as part of the continuing ensemble should the show be renewed beyond the first season.

During his portrayal of Omar Little, Williams went by his character's name and developed a habit of smoking cannabis and an addiction to cocaine in 2004.

For his portrayal of Omar, Williams was named by USA Today as one of ten reasons they still love television. Omar was praised for his uniqueness in the stale landscape of TV crime dramas and for the wit and humor that Williams brings to the portrayal. Omar has been named as one of the first season's richest characters, a Robin Hood of Baltimore's west side projects. The Baltimore City Paper named the character one of their top ten reasons not to cancel the show and called him "arguably the show's single greatest achievement". In 2007 he was nominated for an NAACP Image Award for Outstanding Actor in a Drama Series for his role as Omar.

Williams makes a brief appearance as the shooter at the beginning of the music video for Young Jeezy's "Bury Me a G". He appears in The Kill Point as recurring guest star Q, a police sniper, alongside The Wire co-stars J. D. Williams, Michael Hyatt and Leo Fitzpatrick. He auditioned for the starring role of Mr. Cat but was forced to take a smaller role due to scheduling conflicts; the part of Mr. Cat went to J. D. Williams instead. Williams played a Boston area detective named Devin Amronklin in the 2007 film Gone, Baby, Gone. The film is based on a novel by Dennis Lehane, who has written for The Wire, and was adapted and directed by Ben Affleck. Amronklin is a recurring character in Lehane's Kenzie-Genarro series of books. Williams says that he enjoyed working with Affleck and characterized him as a passionate and hands-on director. The film also featured his co-star from The Wire, Amy Ryan.

In 2008, then-U.S. Senator Barack Obama cited The Wire as his favorite television show, and called Omar his favorite character. About Omar, Obama said, "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."

On July 23, 2011, Community creator Dan Harmon revealed that Williams would star in "at least three episodes" of the sitcom's third season. He played the role of Biology Professor Marshall Kane at Greendale Community College.

In November 2011, it was announced that Williams would appear in Quentin Tarantino's feature film Django Unchained. Williams, who had previously confirmed that he was actually in talks with Tarantino to take on the titular role of Django, was to portray a minor character in the film, but scheduling conflicts with Boardwalk Empire prevented him from doing so.

On May 16, 2012, Williams announced that he was an executive producer of the independent film Snow on tha Bluff, Williams' first film under his company, Freedome Productions. On Power 105.1fm's The Breakfast Club, Williams revealed the June 19 release date for Snow on tha Bluff, describing the movie as "real graphic": "everything that is wrong with the 'hood is in this movie". Williams also shared on The Breakfast Club that he was starring in an African American western, They Die by Dawn, with his co-star Snoop from the HBO series The Wire. Williams also revealed that he was starring in the lead role as rapper Ol' Dirty Bastard (ODB) from the Wu-Tang Clan in the movie Dirty Whiteboy in 2014, which is based on the relationship ODB had with his manager during the last two years of his life. Williams mentioned the role was special to him because he grew up listening to Ol' Dirty Bastard and to Wu-Tang and he is also a Brooklyn native.

He played Teddy, the former boyfriend of Nikki Tru (Kerry Washington) in the Chris Rock film I Think I Love My Wife. He played James, a policeman, in singer R. Kelly's "Trapped in the Closet". He also appeared in The Game's "Dreams" and "How We Do" music videos, Tony Yayo's "It's a Stick Up" music video and Cam'ron's film Killa Season, as well as Trick Daddy's video "Tuck Your Ice In", Sheek Louch's "Good Love", and Young Jeezy's "Bury me a G" alongside his The Wire co-star Hassan Johnson. In 2013, Williams appeared in ASAP Rocky's video for "Phoenix". Williams played the role of The Thief in the 2009 film The Road, an adaptation of the Cormac McCarthy novel of the same name. In 2010, Williams appeared in the film Life During Wartime. The character he played, Allen, was portrayed by Philip Seymour Hoffman in the film's predecessor, Happiness.

In 2013, he starred in MGMT's music video for "Cool Song No. 2" and was featured modeling for The Gap's 2014 fall collection.

On March 9, 2015, it was announced that Williams would star in SundanceTV's Hap and Leonard, based on a series of novels by Joe R. Lansdale. The first season got positive reviews and a six-episode season 2 was aired in 2017.

Also in 2015, Williams appeared in the music video for "The Mephistopheles of Los Angeles" by Marilyn Manson.

In 2016, Williams began working with Vice News, hosting a VICELAND program titled Black Market. In this series, he visits various clandestine markets to explore how they operate while investigating the circumstances that generate their clientele.

In 2018, Williams again worked with the Vice team. In "Raised in the System," the extended premiere episode of the sixth season of HBO’s Emmy-winning weekly news magazine series, Williams embarked on a personal journey to expose the root of the American mass incarceration crisis: the juvenile justice system.

As of 2020, he is playing Montrose Freeman in Lovecraft Country.