Stalker
This isn't really a horror movie but its still one of my favorites. It is a devastating, bleak look at the life of a poor russian family and the heartbreak between them. The man is revealed to be a stalker--a tour guide, of sorts, into the Zone which is a very mysterious and deadly area quarantined by military and police alike full of wonders. Stalker meets up with two men, Professor and Writer, at a bar and they begin to discuss their lives and goals there and finalize some details. This is when you realize two things about the movie: Almost every scene is a work of art in some form or another. The color pallete, the shots, the angles--the entire movie looks spectacular visually and it only gets more and more stunning once you enter the lush Zone.
The other thing is just how good the writing in this movie is. No taboo, no emotional state, is left untouched by these three men as they converse and travel the Zone. The dialog is very fluid and mostly driven on by Writer, an analytical and jaded man who hates Writing but sees nothing better to do with is life. He is the most complicated character in the movie and it really shows. Professor is a quiet, elderly man who keeps to himself but sometimes joins in on Writer's arguments--often taking the role of the other side. Stalker keeps to himself, but mostly butts in about purpose/religion/cruelty of life.
The characters excel and are some of my personal favorites ever on screen. The last thing to mention is the sheer stunning atmosphere The Zone has. It is a creepy, unsettling, mysterious world full of things in the side of the screen and vast imagery and "traps". There are some select scenes that are impossibly tense without doing anything really. The Meat Grinder, for example.
The movie's ending is also my favorite almost of all time. The final 30 minute conversation and struggle between the three men, the moral choices put into action, and the finale are some of the most well executed scenes I have personally seen. It manages to stay atmospheric and unsettling the entire way through without showing any monsters or goblins. Its about human emotion, survival, and the mysteries of The Zone itself