A few mostly unamerican movies:
In Bruges is out on DVD – I’ve ordered it.
No, but it’s showing on HBO so I’ve put it on the DVR list. I’ll search for the other movies mentioned here too.
Double Indemnity – another good one. TCM doesn’t show it often enough. And Anatomy of a Murder – that one never gets tired.
*Don’t Ask, I’ve seen the US version of The Vanishing, but not the Dutch version. I don’t think I could handle it again (claustrophobic). I’ll check out the others on your list, and Syriana. I passed it by when it was on HBO – not sure why.
Thanks, everyone. 
ETA: Looking at IMDB reminded me that I’ve seen The Pledge – great movie. I like ambiguous endings.
A 1962 classic To kill a mockingbird.
Dark, dramatic, with several truly memorable moments.
Wow, someone else actually saw The Quiet Earth? I don’t know why, but somehow you just made my day better, Ed!
Now if you say you’ve seen Straight to Hell, you will have made my week! Not that Straight to Hell fits into any of the OP’s wanna-see categories. It’s not dark, dramatic, or anything like No Country for Old Men. It’s not even that good. It’s a sort-of western comedy starring kind-of rock stars, and it’s just . . . there. Still, I own it on DVD, and while my wife won’t let me watch it if she’s in the same room, I somehow manage to see it once every year or so.
I’ve got some dark for you right here: Miracle Mile
Miracle Mile. Lordy, just thinking about that movie makes me sweat. Good choice. ::shudder::
I loved this movie.
Have you seen American History X? Excellent flick.
But the OP did like No Country for Old Men, which was also pretty violent…IIRC, Before the Devil Knows Your Dead isn’t much, if at all worse. At any rate, I would second your initial suggestion–great suspenseful movie.
Black Narcissus
Fargo
Brazil
The Game
Requiem for a Dream
Blood Simple
Rififi
Boogie Nights
Election (black comedy)
The Night of the Hunter
Shadow of a Doubt
Mildred Pierce
Rashomen
Unforgiven
Million Dollar Baby
Y Tu Mama Tambien (doesn’t really fit in here but has some dark themes)
Leon
Papillon
If you liked the Wages of Fear, see the William Friedkin remake “Sorcerer.” It’s terrific, as well.
There’s a somewhat obscure animated movie called The Plague Dogs. It’s about two dogs who escape from an animal research facility and try to survive on their own in the wild. They’ve both been badly damaged from their time in the labs (one of them has had multiple brain surgeries and has trouble telling what’s real and what isn’t).
It’s terribly bleak and one of the most depressing animated movies you’ll ever see. There is a little bit of violence and gore, but it’s relevant to the story and is over pretty quickly. It’s a hard movie to find, but you can watch the whole uncut version here. Definitely worth a look.
Yeah. It’s gratuitous violence I don’t like.
valley, is Election the one where the creepy guy masturbates in front of his date?
I will definitely take a look at that. Thanks!
Some suggestions:
The Prestige– Battling rival magicians around 1900. Very serious rivals.
*
Atonement-- Very good movie about the cost of youthful mistakes.
*
Croupier–Modern film noir with a wheels within wheels plot.
I assume you’ve already seen Lion in Winter.
Some suggestions:
12 Monkeys
Blade Runner
Children of Men
Dark City
Heat
L.A. Confidential
Last Man Standing
Momento
Mystic River
Reservoir Dogs (might be too violent, but still a great movie)
True Romance (also violent)
Or you might also want to check out Wikipedias list offilm noir.
That wasn’t exactly dark though.
The one where the dude from ER accidently gets a phone call that Russian nukes are inbound? That freaked me out the first time I saw it.
Along with On The Beach and Dr Strangelove, your might also want to check out the following WWIII films:
The Day After
By Dawn’s Early Light
There’s also a film similar to Miracle Mile from the late 90s/early 2000s, but I can’t remember the name of it. It basically followed a number of people trying to reach each other in some city (LA possibly) through the escalating chaos of the coming end of the world. It is never specifically stated what that end is (meteor, nuclear war, etc), but its precise time is know.
The OP might find one particular scene…a bit hard to swallow.
I know a couple scenes you might be referring to, but I think they’re essential to the story. But I agree, they’re both difficult to watch.
How about something a little more domestic?
I watched Ordinary People for the first time last week, and it floored me. Unbelievably well written, well acted and well directed. It left me feeling pretty shredded inside.
While I mostly loathe Robert Redford, he deserves every bit of acclaim he got for this one. And - Wahoo for Judd Hirsch!
The O’Toole-Hepburn version? Yes. Liked it. Haven’t seen a medieval drama I didn’t like. I’m very easy to please there.
Is American History X the one with the curb thing? I might not be up for that.
My favorite movie! I watch it every once in a while when it’s time for a good cry. Timothy Hutton is perfect, as is the ending.
My first thought upon reading the OP was of The Machinist with Christian Bale. Then of Dirty Pretty Things with Audrey Tautou and Chiwetel Ejiofor.
Have you seen Excalibur? Probably my favorite medieval film.
Also the SciFi Channel’s Merlin was campy as hell, but pretty dark and cool at times.
A masterpiece.