Kim Rossi Stuart, who has auditioned for the part of Romualdo at the age of 22, after only two films in the TV series already decided to not want to play his character anymore (his appearance in the fourth film is just with stock footage from the first film) and for this reason every sequel in the series has been developed based on the choices of the actors to stay or leave the cast. Brigitte Nielsen said she based her deliberately over-the-top role on the character of the Evil Queen in Disney's "Snow White"; her role as the Black Witch was received so well by the public that Bava decided to revive the character for three successive chapters of the saga. The character Tarabas was born from the writer Gianni Romo's passion for the comic book series "Dylan Dog", where a character of this name appears in one story.