Williams was nominated for a Golden Globe award for his part in Hair. He got a second Golden Globe nomination for starring in Sydney Lumet's Prince of the City (1981). He got a third nomination for his performance as Stanley Kowalski in the television presentation of A Streetcar Named Desire. In 1996, he was nominated for the Best Actor Emmy Award by the Academy of Television Arts & Sciences for his work in The Late Shift, an HBO movie. Williams has also worked as a director, winning two festival awards for directing Texan in Showtime's Chanticleer series.
Williams' acting career includes numerous stage roles. He won a Drama League Award for his work in the Broadway revival of Stephen Sondheim's Follies, and another for starring in the off-Broadway production of Captains Courageous . Other notable Broadway shows include Grease, the Sherman Brothers' Over Here!, Once in a Lifetime, Pirates of Penzance and Love Letters, and off-Broadway, he has appeared in David Mamet's Oleanna and Oh, Hell (at Lincoln Center), Some Men Need Help, and Randy Newman's Maybe I'm Doing It Wrong. He premiered the Los Angeles production of Love Letters and appeared in War Letters at the Canon Theatre in Los Angeles.
Williams may be best known for his leading role as Dr. Andrew Brown in the former WB series Everwood, about a New York neurosurgeon who moves his family to the fictional Everwood, Colorado. Although the show's ratings were never spectacular, it won critical acclaim and had a devoted following. Williams received two SAG award nominations (2003 and 2004) for his role on the show.
Williams has recently made several guest appearances on the ABC drama Brothers & Sisters playing the role of David Morton, a friend and potential suitor of the Sally Field character. Williams currently stars in a series on the TNT titled Heartland in which he plays, Nathaniel Grant, the head of a Pittsburgh organ transplant center. He also starred in a Lifetime movie called the Staircase Murders, which aired April 15, 2007.