A successful Shakespearian actor on Broadway, William S. Hart went on to become one of the first great stars of the motion picture western. Hart appeared in director Sidney Olcott's 1907 production of Ben Hur for which he received good recognition and more parts in short films until 1914 when he starred in his first feature, The Bargain.

Hart was particularly interested in making realistic western films. His films are noted for their authentic costumes and props, as well as Hart's extraordinary acting ability, honed on Shakespearian theatre stages in the US and England.

In 1917, he accepted a lucrative offer from Adolph Zukor to join Famous Players-Laskey. In 1925, he starred in King Baggot's film Tumbleweeds which was his last and probably most famous for United Artists. Hart's popularity waned when the public began to be attracted to "larger than life" Western stars such as Tom Mix. He retired to his ranch, "Casa de los Vientos" in Newhall, California which was designed by architect Arthur R. Kelly.

Hart was fascinated by the Old West. He acquired Billy the Kid's "six shooters", and was a friend of legendary lawmen Wyatt Earp and Bat Masterson.

Hart married young Hollywood actress, Winifred Westover. Although their marriage was short-lived, they had one child, William S. Hart Jr. (1922-2004).

On his passing in 1946, William S. Hart was buried in Green-Wood Cemetery in Brooklyn, New York.

For his contribution to the motion picture industry, William S. Hart has a star on the Hollywood Walk of Fame at 6363 Hollywood Blvd. In 1975, he was inducted into the Western Performers Hall of Fame at the National Cowboy & Western Heritage Museum in Oklahoma City, Oklahoma.

As part of the Natural History Museum of Los Angeles County, California, Hart's former home and 260 acre (1.1 km²) ranch in Newhall is now "William S. Hart Park". The William S. Hart Union High School District located in the Santa Clarita Valley in the northern part of Los Angeles County was named in his honor.