Le Grand Guignol, famed (and infamous) Parisian playhouse, played a vital role in the development of not just horror cinema, but all of its off-shoots, psychological drama, film noir, and so on.

Concentrating on themes of death, decay, insanity, and other dark subjects, Guignol plays often dealt with transcendence through these themes, and allowed an audience member to confront them if he/she wanted, or to merely sit back and enjoy the plays as chilling, gory escapism. The writing ranged from clever, dramatically engrossing ,and even at times minimalist (ex. At the Telephone), to exploitative, relying heavily on violence and general ghoulishness (which seemed to please its patrons either way).

Utilizing cold, creepy, sometimes Gothic set-pieces, the plays very often placed their focus on a climactic “moment of violence”, which might occur anywhere from once each piece to once each scene. To provide counterpoint and enhance the importance, these “moments of violence” were often heavily stylized and exaggerated against the Grand Guignol’s traditional realism and naturalism.

Obviously, this heavy and unique style translated well into film (film being ultimately what killed the Grand Guignol theatre). Filmmakers have and continue to be inspired by its style and aesthetic, both visually and in writing.

Recommended links:
Grand Guignol Plays
Books about Grand Guignol
Wikipedia Grand Guignol page
Amazon page for The Monster Show by David J. Skal, a pretty good book about horror and culture that touches on the Grand Guignol as a seed for horror films

Of course, this is an ongoing list. Please leave suggestions.

Grand Guignol Cinema