Clarence Williams III (born August 21, 1939) is an American actor.

His first major acting role was as "Linc Hayes" on Aaron Spelling's The Mod Squad. He has guest starred in television shows such as Hill Street Blues, Miami Vice, The Highwayman, Twin Peaks, Star Trek: Deep Space Nine, Everybody Hates Chris, and in a recurring role as Philby Cross in the Mystery Woman movie series on the Hallmark Channel. He has appeared in films such as Deep Cover, Tales from the Hood, Half Baked, and as jazz great Jelly Roll Morton in "The Legend of 1900", but is probably best remembered for his role as Frances L, the father of Prince's character "The Kid" in the hit movie Purple Rain.

Williams was born in New York City, New York. His grandfather was Clarence Williams, the jazz pianist and composer. He was raised by his grandmother. Williams was married to African-American actress Gloria Foster (The Oracle in The Matrix), who died on September 29, 2001. One of Williams' closest friends is actor Eric Braeden.

Williams III's latest portrayal is of Ellsworth Raymond "Bumpy" Johnson (1906–1968) in American Gangster, which was released on November 2, 2007. Johnson was an American gangster in Harlem in the early 20th century. The movie is directed by Ridley Scott. Williams III is not listed in the movie credits for American Gangster 2007 film

As the son of a displaced musician, Harlem-born African-American actor Clarence Williams III was raised by his musical grandparents, the legendary jazz and boogie-woogie composer/pianist Clarence Williams (III), who wrote such classics as "T'Aint Nobody's Business If I Do" and "Baby, Won't You Please Come Home," and blues singer Eva Taylor (1895-1977). While attending a local YMCA as a teen, Williams became interested in dramatics. After a two-year hitch with the U.S. Air Force, he started up his acting career, making a minor New York stage debut with "The Long Dream" in 1960. He continued impressively with roles in "Walk in Darkness" (1963), "Sarah and the Sax" (1964) and "Doubletalk" (1964), and capped his early career with a Theatre World Award and Tony-nomination for the three-person play "Slow Dance on the Killing Ground" (1964). Continuing on with powerful work in "Does a Tiger Wear a Neckie?" (1966) and "King John," Vietnam-era Hollywood finally began to take notice of his "angry young man" charisma. His casting as former delinquent-turned-undercover cop Linc Hayes on the highly popular TV cop series "Mod Squad, The" (1968) along with fellow white partners Michael Cole (I) and Peggy Lipton was a huge break for all three relative unknowns. Sporting a huge Afro, paisley shirts, dark shades and spouting hip language like "dig it" and "solid", the trio showed the requisite anti-establishment defiance and coolness to attract the angry, young generation--while still playing the good guys. Following the series' demise in 1973, he purposely avoid the "blaxploitation" Hollywood scene and returned to the stage, notably on Broadway opposite Maggie Smith (I) in Tom Stoppard's play "Night and Day" (1979). In the 80s he launched an enviable character career in films, often playing a cool, streetwise character or threatening menace. Among his better-known on-screen assignments is the role of Prince (I)'s abusive father in Purple Rain (1984), a burnt-out political activist in the spoof I'm Gonna Git You Sucka (1988), the recurring part of Roger Hardy in the twisted cult TV series "Twin Peaks" (1990), a good-guy cop in Deep Cover (1992), an rioter in the Attica-themed mini-series Against the Wall (1994) (TV) and Wesley Snipes heroin-addicted dad in Sugar Hill (1994), among others. Powerful roles on such shows as "Law & Order," "Profiler" and "Judging Amy" has kept him newsworthy but not strongly in the limelight. Once married to actress Gloria Foster, they appeared together in the movie Cool World, The (1964). Following their divorce, they remained friendly and upon her death in 2001, it was he who made the formal announcement.