2. Blood and Black Lace (1964)
The most important film on this list, Mario Bava basically invented the Giallo with this picture. The plot is fairly slim - a man with a flesh coloured mask (which looks groovy in a 1960s kind of way) is viciously murdering models in a fashion house. There are five male suspects but they all have foolproof alibis. The slaughter continues to its grim finale. The outrageous, elaborate kill scenes by a masked man with black leather gloves have come to typify the very essence of what a Giallo is about for fans of the genre. It doesn't matter about limited plot mechanics such as motivation, what matters are well staged murder scenes and a good mystery who dunnit. Of course Bava brings his own unique skills to the picture. The film is beautifully lit (lighting was Bava's speciality). Blood and Black Lace was a fancied Up title. The original title - Six Women for the Killer - shows you the intent of the film and it does exactly what it says on the tin.