Taxidermia (Being devoured by cats, gluttony, self mutilation and all around WTF), Ratcatcher (Kids, rape, bullies, suicide), Tyrannosaur (Regret, anger, hate, abuse, fake happiness), Happiness (pedo, loneliness, desperation), House of Sand and Fog (Losing a love one, out of place, and suicide), Manchester by the sea (Misery, unable to forgive oneself. Not disturbing but good.), Me and Earl and the Dying Girl (Not that dark but worth a watch, cancer and death), Cannibal Holocaust (Actual animal mutilation), and L.I.E. (pedo, depression, lost, broken family.) That is a good start. I have been told to watch A Serbian Film and Antichrist but haven't got around to those yet.