Born William December Williams Jr in Harlem, he began his career as a child, thanks in part to his mother, an elevator operator at Broadway's Lyceum Theater. When she discovered that a production of "The Firebrand of Florence" starring Lotte Lenya needed youngsters, she volunteered her son. After that brief success, however, Williams returned to a relatively normal upbringing until he resumed his performing career as an adult to help fund his studies as a painter. TV roles and stage work followed and Williams went on to train with Paul Mann, Herbert Berghof and Sidney Poitier. After making his feature debut in 1959's "The Last Angry Man", he debuted on Broadway the following year and spent much of the 1960s alternating between the small screen and the theater. It wasn't until he was cast as real-life football player Gale Sayers in the seminal TV-movie "Brian's Song" (ABC, 1971) that Williams' career took flight.
Once cast in romantic roles opposite Diana Ross in both "Lady Sings the Blues" and "Mahogany" (1975), Williams seemed poised for major stardom, but good roles for men of color were not easy to land. One of his best was as a baseball player who forms his own team as a rival to the All Negro League in the underrated "The Bingo Long Traveling All-Stars and Motor Kings" (1976). Williams also delivered a strong portrayal of ragtime musician "Scott Joplin" (1977), but the film's made-for-television's origins marred its reception.
As the 80s dawned, George Lucas tapped him to play the scoundrel Lando Calrissian in "The Empire Strikes Back" (1980) which he reprised in "The Return of the Jedi" (1983). Unfortunately, most of Williams' later films were unworthy of his talents, although he had a good turn as the district attorney Harvey Dent in 1989's "Batman". (For some reason, Williams was overlooked for the second sequel in which Dent's character morphed into Two Face and Tommy Lee Jones inherited the role.)
Throughout the 80s and 90s, the small screen offered occasional roles that made the best of Williams' assets. He was duly smooth and charming as a love interest for Diahann Carroll on ABC's "Dynasty" in 1987. Williams also won strong praise for his portrayal of Motown founder Berry Gordy in the ABC miniseries "The Jacksons: An American Dream" (1992), During this period, the actor, who became financially secure thanks to the success of the "Star Wars" films, resumed his avocation as a painter and had several exhibitions of his work.
Williams had small roles in film and television for the next several years, including the comedies "The Ladies Man" (2000) and "Undercover Brother" (2002). In 2000, Williams co-starred in the independent drama "The Visit," directed by Jordan Walker-Pearlman. Williams received widespread praise for his portrayal of a stern yet loving father. The favorable feedback whetted William's appetite to revive his career as a serious character actor. In 2002, he was set to star in Walker-Pearlman's next project "Constellation."