Treat Williams has been a renowned actor on Broadway, in films, and on television for more than 30 years. Along the way he has been seen in such greats as Hair, A Streetcar Named Desire, Mulholland Falls, Deep End of the Ocean, and Woody Allen's Hollywood Ending. It was the WB television series Everwood, however, that brought him to the attention of audiences everywhere. He has received much critical acclaim and several award nominations for his portrayal of the endearing Dr. Andy Brown, a surgeon who moved his family from New York City to a small town in Colorado after his wife died.

Williams was named after his ancestor Robert Treat Payne (1731-1814), one of the men who signed the Declaration of Independence. Williams was born on December 1, 1951, in Rowayton, Connecticut. He grew up there attending prep-school before he went on to Franklin and Marshall College in Pennsylvania. While there he joined the Fulton Repertory Theatre Troupe in Lancaster. He thoroughly explored his love of acting while part of the Troupe and so after graduation he moved to New York City to try acting as a full-time career. Soon after his move, in 1973, he made his Broadway debut in the musical Grease. He started out as an understudy to John Travolta but later ended up taking over the role of Danny Zuko himself. His plan to enter the New York acting scene began with great success. He was later seen in productions of Over Here, a play that featured the Andrews Sisters, The Pirates of Penzance, and Oleanna.

Williams decided to try his hand at film acting and soon after made his film debut in the farcical movie The Ritz in 1976. He played a private detective who was tracking a mobster through ridiculous situations. It was in 1979's Hair, however, that Williams caught the public's eye. He was nominated for a Golden Globe award for New Star of the Year for his portrayal of the character Berger, the leader of a group of hippies. Around the same time, Williams, who has always been interested in singing as well as acting, formed a rock band with Kevin Kline, Rex Smith, Peter Riegert, and Mary Elizabeth Mastrantonio called Crime & Punishment.