I recently saw “Rampage” from 2009. Its basically a movie where a spree shooter is portrayed as the good guy/anti-hero. Several parts gave me that pit in your stomach, teeth gritting uncomfortable moment. I really hated it. Although I’m not surprised there are sequals I am disappointed and will not be watching them.
Most I can think of have been mentioned elsewhere in this thread, like Trainspotting, Blue Velvet, Old Boy. If you know about Requiem, you probably know about π by the same director, but I’ll mention it just in case. Ooh here’s a good one I should have put in the main thread, too late now lol: Die Welle (The Wave). It’s a German drama that takes place in a high school, that’s all I’ll say about it, but it’s really good.