I second Tad Williams trilogy Memory Sorrow & Thorn - it's one of my fav ;]
http://en.wikipedia.org/wiki/Memory,_Sorrow,_and_Thorn

I'm not sure if that's what you're exactly looking for but The Sword of Truth by Terry Goodkind is really good and in my opinion it's quite dark at the moments
http://en.wikipedia.org/wiki/The_Sword_of_Truth

If you're interested in the tv series there is one losely based on the Sword of Truth novels. It's called Legend of the Seeker. It's not as dark as the book but still a nice piece of fantasy to watch imo ;]
http://www.imdb.com/title/tt0844653/

Ok, so maybe.... just maybe, i joined this forum solely to answer your request... i'm weird like that.

Books:
The Night Angel Trilogy by Brent Weeks - Extremely good, very dark, one of my all time favorites.
The Robin Hobb Books - Not very dark, but very good.

For manga:
Vagabond by Inoue Takehiko - not very dark
Threads of Time by Noh Mi-Young - again, not very dark
Cavalier of the Abyss by Ga On-Bi - a hell of a lot darker than its prequel Immortal regis, and it only gets darker through the story.

So from a fellow passionate reader, hope i could help.

Well, I haven't read many novels that deal with "dark" medieval fantasy... and most of the time, a stories ambiance is up to you. You can read it as is or force it to take you to a light-hearted environment or the opposite.



For manga:
Wolfsmund may work... but it seems a bit like a comedy... a black comedy, but comedy none-the-less.

However, Akazukin to Yasashii Ookami would be right up your alley.

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"Officially, this machine doesn't exist, you didn't get it from me,
and I don't know you. Make sure it doesn't leave the building."

..I don't know how to quote. But yes, the WoT has most of the things you mentioned, its just, I guess, the tone is written in a "lighter" way. I totally agree with the above assessments of the WoT.

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Night gathers, and now my watch begins. It shall not end until my death. I shall take no wife, hold no lands, father no children. I shall wear no crowns and win no glory. I shall live and die at my post. I am the sword in the darkness. I am the watcher on the walls. I am the fire that burns against the cold, the light that brings the dawn, the horn that wakes the sleepers, the shield that guards the realms of men. I pledge my life and honor to the Night's Watch, for this night and all the nights to come.
-Oath of the Night's Watch, A Song of Ice and Fire

the night angel trilogy is excellent. darker than most books. however, how dark it is is an opinion. look it up and find out.

I think this one series starting with "Gardens of the Moon" fits this description. Should check it out. *sorry i dont know how to link to the text*

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An instant or an eternity. Both are the same, in the passing of an instant lies the beauty of eternity.
-Ginen Shounen

"It is now time to leave-for me to die, and for you to live-though which of us has the better destiny is unclear to everyone, save only to God."
- Plato

The series is called Malazan Book of the Fallen, and I second it. Also the Wheel of Time and the Dark Tower series

Awesome! There's so many to choose from!
The Dark Tower Series and The Night Angel Trilogy caught my interest!

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Rape is imminent.

The Dark Tower series isn't medieval... it's a future world that has a western feel to it... with technology from today that they don't use.

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"Officially, this machine doesn't exist, you didn't get it from me,
and I don't know you. Make sure it doesn't leave the building."

I always put my trust on Stephen King's works. I can't believe I almost missed on this one.


________________

Rape is imminent.

It still has kingdoms, kings, knights, etc. Stephen king was trying to combime elements of LOTR and spaghetti westerns. So I would say plenty of parts in Dark Tower have the feel of medieval.Even if one doesn't, it fits a lot of the other points the OP was looking for and its just awesome.

does the "Grimm's Fairy Tales" fit??

If you like Stephen King's books then it's a must read! There's plenty of references to Dark Tower in other King's books, some of them are even impossible to be understood without knowing it.

Robert E. Howard wrote the best dark fantasy storys that i read until now, Conan, Solomon Kane, and there was some templar storys too.

If you are looking for dark you might enjoy:

At lest the first book of The Black Jewels Trilogy by Anne Bishop

The Wit’ch War Saga by James Clemens

The Noble Dead novels by Barb and J. C. Hendee also have dark elements and vampires in a world with elf's and other classic fantasy elements, I found it interesting.

I also strongly second (or third or whatever ) Malazan Book of the Fallen by Steven Erikson

And even though I haven't read to much of it you might consider The First Law series by Joe Abercrombie