He also appeared in films such as Purple Rain, 52 Pick-Up, Tales from the Hood, Hoodlum, Half Baked, Life, American Gangster, and Reindeer Games.

[5] His breakout theatrical role was in William Hanley's Slow Dance on the Killing Ground, for which he received a Tony Award nomination.

The New York Times drama critic Howard Taubman wrote of his performance, "Mr. Williams glides like a dancer, giving his long, fraudulently airy speeches the inner rhythms of fear and showing the nakedness of terror when he ceases to pretend."

After the series ended in 1973, he worked in a variety of genres on stage and screen, from comedy (I'm Gonna Git You Sucka, Half-Baked) to sci-fi (Star Trek: Deep Space Nine), and drama (Purple Rain).

Spanning over forty years, his career included the role of Prince's tormented father, who was also a musician, in Purple Rain (1984), A guest appearance in Miami Vice (1985), a recurring role in the surreal TV series Twin Peaks (1990), a good cop in Deep Cover (1992), a rioter in the mini-series Against the Wall (1994), and Wesley Snipes' chemically dependent father in Sugar Hill (1993).

His other roles on television include Hill Street Blues, the Canadian cult classic The Littlest Hobo, Miami Vice, The Highwayman, Burn Notice, Everybody Hates Chris, Justified, Cold Case, and Law & Order.