Short answers, pulled from the story.
Both Charles L. Grant and Karl Edward Wagner are credited with coining the term "dark fantasy", though they were describing different styles of fiction. Grant used it for atmospheric horror stories in which humanity faces forces beyond understanding, while Wagner used it to describe fantasy fiction featuring anti-heroic protagonists such as his Gothic warrior Kane.
Gertrude Barrows Bennett has been called "the woman who invented dark fantasy". Her work predates the coinages attributed to both Charles L. Grant and Karl Edward Wagner.
Brian Stableford defines dark fantasy as a subgenre of stories that attempt to incorporate elements of horror fiction into the standard formulae of fantasy. He further distinguishes it from contemporary fantasy by setting: supernatural horror in secondary worlds qualifies as dark fantasy, while supernatural horror set in the real world is contemporary fantasy.
Anne Rice's The Vampire Chronicles, Chelsea Quinn Yarbro's Saint-Germain, and Neil Gaiman's The Sandman are cited as early examples of dark fantasy that presents a sympathetic view of supernatural beings. These works differ from traditional horror by focusing on the creature's perspective rather than on victims and survivors.
FromSoftware's Dark Souls series, Bloodborne, and Elden Ring are praised as exceptional representations of the dark fantasy genre. The 2013 action role-playing game Dragon's Crown is also cited for its dark fantasy elements, including werewolves, vampires, zombies, homunculi, and human-monster hybrids.
Berserk, created by Kentaro Miura and debuting in 1989, is frequently noted as a dark fantasy example due to its extreme violence, moral ambiguity, apocalyptic storylines, and anti-hero protagonists. Attack on Titan is also described as dark fantasy for its intense violence and dystopian setting.