In 1957, Clarence Williams III began his film career with a small part in ‘Dark of the Moon’. But very soon, he was called for his military service; serving for two years as a paratrooper in 506th Infantry. On being released, he returned to the stage, participating in various productions.
In 1960, he debuted on Broadway with ‘The Long Dream’, appearing in it in the role of Chris. Thereafter, he continued to perform in various productions like ‘Walk in Darkness’ (1963) and ‘Sarah and the Sax’ (1964), meanwhile also appearing in the film ‘The Cool World’ (1963).
In late 1964, he got his breakthrough role, when he was cast as Randal in William Hanley's ‘Slow Dance on the Killing Ground’. It opened on November 30, 1964 at Plymouth Theatre and closed on February 13, 1965 after 88 performances. It not only earned him great reviews, but also Tony Award nomination.
In 1965, he debuted on television with one episode of the NBC series ‘Lamp Unto My Feet’. Thereafter, he continued working both on screen and stage, appearing in plays like ‘The Great Indoors’ (1966), ‘King John’(1967), ‘The Party on Greenwich Avenue (1967),’ and ‘Does a Tiger Wear a Necktie?’ (1967).
In 1968, he got his second breakthrough when he was cast as Linc Hayes, on the highly popular television cop series, ‘The Mod Squad’, remaining with it till its end in 1973. Meanwhile in 1970, he appeared as a narrator in ‘King: A Filmed Record... Montgomery to Memphis’(Documentary).
As ‘The Mod Squad’ ended in 1973, he returned to the stage, unwilling to be typecast in typical black roles. He was part of well-known plays like ‘Night and Day’ (1979-1980) and ‘Suspenders’ (1979). Also in 1979, he reprised the role of Linc Hayes in television film, ‘The Return of Mod Squad’.
In 1980s, he returned to the screen, appearing in films like ‘Purple Rain’ (1984), ’52 Pick-up’ (1986), 'Tough Guys Don't Dance' (1987) , 'Perfect Victims' (1988) and 'I'm Gonna Git You Sucka' (1989). Concurrently, he also began appearing on television, doing numerous episodic works during this period.
From 1991, he became more regular on big screen, starring in ‘Tales from Hood’ in 1995, ‘Hoodlums’ in 1997, ‘The Legend of 1900’ and ‘Half Baked’ in 1998. Other important works of this decade include 'My Heroes Have Always Been Cowboys' (1991), ‘Deep Cover’ (1992), ‘Deadfall’ (1993), ‘Sugar Hill’ (also known as Harlem ) (1994) etc.
Also in 1990s, he appeared in several television series, most important of them being the recurring role of FBI agent Roger Hardy in ‘Twin Peaks’. In addition, he also did numerous other episodic works in popular television series like ‘Star Trek’, 'Jake and the Fatman', 'Tales from the Crypt’ etc.
Continuing to work both in films and television series, he played the role Cassius Clay, Sr. in the television film, ‘Ali: An American Hero’ and that of Merlin in ‘Reindeer Games’ in 2000. Appearing as Philby in ten ‘Mystery Woman’ (2005- 2007) made-for-television films was another hallmark of the decade.
In 2009, he starred as Mac in ‘The Way of War’, also appearing in films like ‘The Extreme Team’ (2003), ‘Constellation’ (2005), ‘The Blue Hour’ (2007), ‘American Gangster’ (2007), ‘A Day in the Life’ (2009). His last film, ‘Snowbird’, in which he starred as Bob, was released in 2016.