Firmin Swinnen (1885–1972) was a Belgian theater organist and concert artist who was noted for his organ improvisations during silent films in New York City.

Born in Montaigu, Belgium, Swinnen became an organist at the Antwerp cathedral, until World War I caused him to flee to the UK.

He played the organ pedal keyboard solo part in the concerto version Mr. Frank Stewart Adams wrote for the opening Allegro of Widor's Fifth Symphony.

Commentators noted that "Few men can improvise musically interesting caprices, scherzos, toccatas, and gavottes by the hour".

The instrument, which spoke into the conservatory ballroom, was used for charity concerts in the indoor tropical gardens.