- Country: Italy
- Genres: Comedy, Mystery, Thriller
- Release: 1977-10-01
- Director: Luigi Zampa
- Writers: Sergio Donati
- Language: Italian
- Stars: Johnny Dorelli , Sydne Rome , Renzo Palmer , Yves Beneyton , Enzo Santaniello , Henning Schlüter , Renato Scarpa , Gianrico Tedeschi , Orazio Orlando , Salvatore Baccaro
- Runtime: 94 min
- Awards: N/A
- AKA: Im Dienste eines Monsters (Germany) , The masters (Sweden) , O daimonas (Greece) , Il mostro , A rém (Hungary) , Il mostro (Italy) , Qui sera tué demain? (France, French Republic) , Criminalia (France, French Republic) , Il mostro (Japan) , Potwór (Poland) , El monstruo (Spain) , The Fiend
- Plot: A low rank journalist at Tribuna Sera newspaper receives a letter one day. His correspondence contains a serial killer's letters, which he exploits.
- IMDB:tt0076411
Il mostro Cast · · · ALL
Luigi Zampa
Director
Johnny Dorelli
Valerio Barigozzi
Sydne Rome
Dina
Renzo Palmer
Baruffi
Yves Beneyton
Giorgio Mesca
Enzo Santaniello
Luca
Henning Schlüter
Nicola Mesca
Renato Scarpa
Livraghi
Gianrico Tedeschi
Nonno Gustavo
Orazio Orlando
Pisani
Salvatore Baccaro
Lupo cattivo
Angelica Ippolito
Anna
Carlo Reali
Brigadiere
Vittorio Zarfati
Avvocato
Mauro Vestri
Segretario al giornale
Clara Colosimo
Donatella Domenica Donati
Renzo Rinaldi
Guerrino Crivello
Carlo Demi
Giuseppe Terranova
Omero Capanna
Guy with camera