Henri, Portait of a Serial Killer - John McNaughton - USA - (1986)

http://www.imdb.com/title/tt0099763/ 

Plopt from Imdb: "Henry likes to kill people, in different ways each time. Henry shares an apartment with Otis. When Otis' sister comes to stay, we see both sides of Henry; the "guy-next-door" and the serial killer."

Considered by many, including myself, as a masterpiece of "psycho-killer" cinema, "Henry..." doesn't offers clues as why does he kill or what triggers his killing. It, as the title says, only show you the everyday life of Henry. And it's remarkably uneventful, apart for the gruesome murders. This characters is empty and just act as a vessels for his killing urges. There's nothing to understand, there's nothing to be done. Just acknowledge the fact that Henry is a killing machine. A highly disturbed killing machine. We don't get to hear his thoughs and we don't see his whole life spanning before our eyes, it's only a "diary" of what's happening during a certain moment in his life and nothing more. It's not exhaustive, it's not psychological, it's not a biopic per se. This leave you with the facts, and nothing else.
The murders in themselves are revolting, as they are not cinematographic and are paced in real time. Stabbing someone takes time, well, in this movie, it takes time. And it's not pleasant. It was the first time I saw something close to reality and it was very impressive. John McNaughton plays also with the notion of "voyeurism", our position in this movie, as the two psychos record some of their murders on tape and watch them over and over, drinking beer on the sofa, like they would watch Baseball on a Sunday afternoon.  Like us watching this movie. Scary shit.
This movie still is one of the creepiest of the "psycho-killer" genre and one of my favorite. Its influence on genre movie is still huge. A cult movie indeed.

Trailer: