Treat Williams (born December 1, 1951) is an American actor who has appeared on film, stage and television over the course of his career. From 2002 to 2006, he was the star of the popular television series Everwood.

Williams was born Richard Treat Williams in Norwalk, Connecticut, the son of Marion (née Andrew), an antiques dealer, and Richard Norman Williams, a corporate executive. He was named after his ancestor, Richard Treat, (1584 - 1669) an early New England settler and a Patentee of the Royal Charter of Connecticut, 1662. Williams graduated from the Kent School in Connecticut and Franklin and Marshall College.

Williams came to world attention when he starred in the Miloš Forman film Hair (1979). This film was based on the Broadway musical Hair. Since that time he has gone on to appear in over seventy-five films and several television series, including, most notably, 1941 (1979), Once Upon A Time In America (1984), Dead Heat (1988), Things to Do in Denver When You're Dead (1995) and Deep Rising (1998).