Incubus (1966)

Incubus (Esperanto: Inkubo) is a 1966 American horror film directed by Leslie Stevens. It was filmed entirely in the constructed language Esperanto, shortly before its star, William Shatner, began his work on Star Trek. The film's cinematography was by Conrad Hall, who went on to win three Academy Awards for his work on the films Butch Cassidy and the Sundance Kid, American Beauty, and Road to Perdition.

Incubus was the second feature film to use Esperanto, following the 1964 film Angoroj. The use of Esperanto was intended to create an eerie, otherworldly feeling, and Stevens prohibited dubbing the film into other languages; however, on the Special Features section of the DVD the makers claim that Esperanto was used because of perceived greater international sales. Esperanto speakers are generally disappointed by the pronunciation of the language by the cast of Incubus. The film was considered to be lost for many years, until a copy with French subtitles was found at Cinémathèque Française in 1996.