Okay I try to list those from this that I haven´t seen.
The Bird with the Crystal Plumage
The Black Cat
The Cook The Thief, his Wife and her Lover (I know how it ends, though…)
The Dr Mabuse films
Eyes Without A Face
Hour Of The Wolf (Bergman)
The Kingdom (Lars Von Trier)
Masque Of The Red Death (on german amazon prime, though!)
Salo (though I´m familar with it and many individual scenes)
The Seventh Victim
A Chinese Ghost Story
Out of those I consider Eyes Without A Face and Peeping Tom the most glaring ones. That list seems a bit longer than it is because it includes original titles for international movies, too.