Wilson was born in Atlanta on March 29, 1942, to Jewel and Thomas Wilson. He attended high school in Atlanta through his junior year but graduated in 1960 from Thomasville High in Thomasville, after his widowed mother moved the family to her hometown.
He entered Southern Polytechnic State University (later Kennesaw State University) in Marietta on an athletic scholarship but was released due to health problems. Wilson then hitchhiked to California, arriving in 1961, and soon enrolled in an acting class. More than five years later, Wilson was cast in the Academy Award–winning movie In the Heat of the Night (1967), with Rod Steiger and Sidney Poitier. This performance was swiftly followed by one of the most sought-after roles of the decade: Richard Hickock, one of two murderers in Richard Brooks’s film adaptation of Truman Capote’s In Cold Blood (1967).
In addition to Brooks, Wilson worked with such noted film directors as Robert Aldrich, John Frankenheimer, Norman Jewison, and Sydney Pollack. His filmography includes The Gypsy Moths (1969); The Great Gatsby (1974); The Ninth Configuration (1980), for which he was nominated for a Golden Globe; and The Right Stuff (1983). For On the Line (1984), a U.S.-Spanish production, Wilson was Best Actor cowinner at the Cartagena Film Festival in Colombia.
Wilson was granted two audiences with Pope John Paul II resulting from his performance in Our God’s Brother (1997), a film adaptation of a play written by the pontiff as a young man. The film was directed by critically acclaimed Polish director Krzysztof Zanussi, with whom Wilson had also worked on the production The Year of the Quiet Sun (1984), which won the Golden Lion at the Venice Film Festival.
Wilson’s later work includes Dead Man Walking (1995), Pearl Harbor (2001), Monster (2003), and Junebug (2005). Beginning in 2007 Wilson appeared as the Reverend Potter in the television series Saving Grace, starring fellow Georgian Holly Hunter and airing on TNT, a network of Turner Broadcasting System. In 2011 he joined the cast of the hit television series The Walking Dead, playing the role of Herschel Greene. Wilson also had a recurring role on the Netflix series The OA.
Active in the Screen Actors Guild, Wilson was an advocate for working actors. He saved guild members millions of dollars in 1992 and 2002 by working to defeat proposals that would have allowed agents to charge new commissions on income from residuals, which are payments made to actors when their work is reshown (as with television reruns) after the initial appearance.
Wilson was married to Heavenly Koh Wilson, an attorney and artist. He died on October 6, 2018, at his home in Los Angeles.