Monsieur Verdoux, 1947
Dir: Charlie Chaplin
Chaplin goes seriously dark and it actually fits him and the style of film that he makes really well. This was originally written by Orson Welles, who wanted Chaplin to play the lead, but Chaplin refused to be directed by anyone else and bought the script and reworked it to suit his own style. It's hard to say what would have been better, but having this is good enough.
Chaplin plays a serial killer (who goes by many aliases) who seduces women (a modern "Bluebeard") and takes all of their money. He had been a respectable banker until a financial meltdown, and when he couldn't find new employment, he decided to start his own "business." He has a wife and son from his previous life, who adore him, but he spends most of his time running around France either meeting (and killing) the women he has already wooed or trying to bag new ones. There are people on his trail though that have to be evaded, not to mention the looming possibility of another economic crisis.
Some of the voice-over is annoyingly expositional, and at the end, when Verdoux is on trial, he gives this big speech about how everyone cares when a single man kills, but when mass killings (war) takes place it is championed. It didn't really need to be said, as there were undertones of it running through the whole film. Other than that though, this is thoroughly enjoyably, and as a fitting dark comedy, Chaplin actually makes murder awkwardly funny.