Grimdark Fantasy is an oft debated sub-genre both in its value and its definition. Joe Abercrombie argues in a blogpost on his website that Grimdark Fantasy, gritty fantasy, is a reaction to the clean, romantic-heroic fantasy that has come before, it is a counterbalancing to a more straightforward style of fantasy. He believes "there's a great deal more to grit than a capacity to shock and titillate" and that the still developing sub-genre is worthwhile. It is a counterbalance to the fantasy that came before and it influences the landscape of fantasy now.
So, what is Grimdark? Let's pull out the old dictionary and break it down. Grim: forbidding or uninviting; depressing or worrying; black, mirthless. Dark: with little or no light; the absence of light. These definitions indicate a world filled with negativity. Indeed, it may be easiest to understand Grimdark with the use of a negative definition: Grimdark Fantasy is not a happy story, it is not glamorized, it is not airbrushed or cleaned up or glossed over, it is not a story where protagonists cooperate to overcome the 'real' evil and save the world, it is not a world where there is a clear path, the story does not end in smiles and merry-making. The sub-genre drips with misery, hopelessness, violence, blood, darkness, morally ambiguous protagonists, anti-heroes, horrible decision making, and a bleak sense of humor.
Grimdark Fantasy is the grittiest of fantasy sub-genres—it is dark, cynical, violent, dirty, and morally ambiguous. It also has a feeling of honesty/realism. But this honesty is skewed because it is built on larger than life situations—the epic. Things are exaggerated for effect (which is good for readers, because these situations make for interesting stories). Grimdark writers aren't trying to create true realism, but they do recognize the unpredictability of life. Anyone can, and will die; let the blood rain down. Readers will undoubtedly be saying "What the fuck?" several times while reading a Grimdark story or just flat out chucking a book across the room. The situations may be epic, but the reactions and behaviors of characters seem real enough. The unpredictability makes the story feel more real because the threats on characters are real, which creates tension.
Moderate. Grimdark is not like Epic Fantasy, the building of a magic system is not an important part of the storytelling here. Magic is there, but its presence is more subtly woven into the story's threads.
Moderate-High. Grimdark Fantasy creates a world that sees the world in shades of grey and some black. Sometimes characters compromise with evil, sometimes it's about the greater good rather than good and evil. The implication is that nothing is completely good or completely evil. There is no legendary King Arthur who will return and solve all the social ills—gritty.
Grimdark fantasy makes readers look at characters, and humans in general, as flawed. Humans are capable of terrible acts: war, racism, sexism, homophobia, violence, and so on.
High. Strong characters are typical of this sub-genre. If there is a glittering knight, you can bet there's some skeletons in his closet. There are no costume cues to indicate a character's disposition, instead characters have individual needs and motivations that are complex and sometimes conflicting. This characteristic of the sub-genre, that seems to mirror the messiness of reality, is part of why some people describe Grimdark Fantasy as honest.
Grimdark brings the story back to the character. Whereas Epic Fantasy focused on setting, maps, monsters, and systems of magic, Grimdark gets into the thick of things with the characters. Stories are often told with a tight narrative voice so that readers get a sense of how the character sees and experiences the world.
Moderate with lots of complexity. Oh you will find action packed plots, you will find complex plots made more complicated by manipulating characters. There will be consequences and twists you didn't see coming because in this sub-genre anything can and does happen. But, at its core, Grimdark is a sub-genre focused on character.
Gratuitous and graphic. Some may even say Grimdark is excessively violent.
Epic Fantasy. Grimdark Fantasy offers epic tales, but grittier and on a narrative level closer to the character.
Dark Fantasy. Dark fantasy combines elements of horror with fantasy. Grimdark definitely has a dark and often gloomy atmosphere, much like horror stories, and so has atmospheric similarities.
Gritty Fantasy. Gritty and Grimdark are often used interchangeably, and they do have much overlap, but Grimdark has a kind of mood and atmosphere that Gritty Fantasy doesn't necessarily have.
By Mark Lawrence. The world is in chaos. The main protagonist has suffered many traumas which leaves him broken, damaged, and willing to lay out body after body in his quest.
By Joe Abercrombie. This series drags epic fantasy into the 21st century with grit, moral ambiguity, explicit violence, and well-rounded/flawed characters.
By George R.R. Martin. Dark, gritty, unpredictable—enough said.
By Steven Erikson. This ten volume series is complex and epic in scope with nonlinear storylines.
By David Gemmell. This series is about the history of a long-standing nation that faces many threats, and also its heroes. Characters are sympathetically flawed, emotionally complex, and struggle with their own issues when faced with truly epic events. Revenge, treachery, suffering, temptation.
By Stephen King. King's magnum opus is a dark epic fantasy. It is a crude and violent story filled with moments of incredible tragedy.
By Glen Cook. An elite mercenary unit is the focus of this series. It is a mix of fantasy, gritty realism, and military fiction. It is often cited as an inspiration for the Grimdark sub-genre.
By Richard K. Morgan. An incredibly dark and gritty epic fantasy that embodies the reaction to shiny fantasy stories. It subverts most traditional fantasy tropes.
By Scott Lynch. Not all Grimdark lacks humor. This series blends the darkness of Grimdark Fantasy with some lighter, comedic moments.
By Elizabeth moon. The fourth book in the Legend of Paksenarrion series. War and heroism have a cost, violence is not without consequences. The book though, is about the characters and how they deal with this reality.