A theatre organ (also known as a theater organ, or [especially in the U.K.] a cinema organ) is a distinct type of pipe organ originally developed to provide music and sound effects to accompany silent films during the first 3 decades of the 20th century.

Theatre organs are usually identified by the distinctive horseshoe-shaped arrangement of stop tabs (tongue-shaped switches) above and around the instrument's keyboards on their consoles. Given their prominent placement in houses of popular entertainment, theatre organ consoles were typically decorated in gaudy ways, with brightly colored stop tabs, and painted bright red and black, or solid gold, or ivory with gold trim, with built-in console lighting. In organs installed in the UK, a common feature was large translucent surrounds extending from both sides of the console, with internal colored lighting. A spectacular original example is the so-called Rhinestone Barton, installed in 1928 in the former RKO Iowa Theatre (now home to Theatre Cedar Rapids in Cedar Rapids, Iowa). The console of this 3 manual 14 rank Wangerin-built Barton is completely covered in black felt fabric embedded with glass glitter in swirling patterns, with all edges trimmed with bands of rhinestones. Another original example is the 3/13 Barton from Ann Arbor's historic Michigan Theatre. The organ was installed in 1927 and is currently played five nights during a week before most film screenings. As the concept of the theatre organ was embraced, theatre organs began to be installed in other types of venues, such as civic auditoriums, sports arenas, private residences, and even churches. One of the largest theatre organs ever built (and certainly boasting the largest console ever built for a theatre organ) was the 6 manual 52 rank Barton installed in the massive Chicago Stadium.