The Chestnut Street Opera House was a theatre located at 1021–1029 Chestnut Street in Philadelphia, Pennsylvania. Built by theatre impresario Robert Fox on the former site of the Pennsylvania Academy of the Fine Arts, it opened as a venue for vaudeville in 1870 as Fox's New American Theatre. The theatre was destroyed by fire in 1877 and was rebuilt that same year. After being acquired by George K. Goodwin, the theatre was remodeled, renamed the Chestnut Street Opera House, and re-opened as a legitimate theatre in 1880. It continued to operate as a legitimate theatre, first under the management of theatre magnates Samuel F. Nixon and J. Fred Zimmerman Sr., who acquired the theatre's lease in 1882, and later under the Shubert Organization, who acquired the theatre in 1916. It was still considered one of Philadelphia's leading legitimate theatres during the 1920s and 1930s. The theatre was also used as a venue for films and was a model theatre for the Triangle Film Corporation in 1915–1916. The theatre closed in 1939 and was demolished in 1940.

Triangle Film Corporation was a major American motion-picture studio, founded in July 1915 in Culver City, California and terminated 7 years later in 1922.