Well, since you asked...
"Gnole", or its modern spelling, "gnoll", is a pejorative term originally referring to a specific African shamanist cult, but that has since expanded into a general slur. Its first written reference occurs in Lord Dunsany's short story, "How Nuth Would Have Practiced His Art Upon The Gnoles" (1912), and reappears in Margaret St. Clair's "The Man Who Sold Rope to the Gnoles" (1951). The word is believed to derive from the Middle English
noll, meaning an idiot or drunkard. In both stories, the gnoles are portrayed as shady and sub-human (indeed, in the latter they are not human at all), physically removed from civilized English society, dwelling in a freakish fantasy realm: "the trees themselves were a warning," they "did not wear the wholesome look of those that we plant ourselves" (Dunsany). St. Clair describes their domain as "the very edge of Terra Cognita" in what is clearly an allusion to the 'black continent' stereotype. In both stories, the Europeans cheat these 'lesser' people out of valuable resources: St. Clair's protagonist Mortensen barters rope for precious gems, and Nuth and Tonkers seek to rob the gnoles of emeraldsrecall, earlier in the story, mention of valuables that Parisian jewellers "could not match [...] without sending specially to Africa" (Dunsany).
Dunsany evidently never travelled to the continent he wrote about, since the physical description of the gnoles themselves is non-existent; a good literary technique for instilling anxiety and apprehension, but a complete disservice to the historical record. St. Clair is little better, describing them as "a little like a Jerusalem artichoke made of India rubber", with no ears, an anteater-like face, and eyes quite literally resembling gemstones. A much more accurate depiction of the cult comes courtesy of Professor Gareth Gygax, who compiled the first detailed overview in 1977, drawing largely on folktales and personal accounts from regional inhabitants. The "gnolls" themselves (as Gygax spells the term) were apparently either human volunteers in or spiritual manifestations resulting from an animist ritual to aid the tribe in times of war: the end product was what can best be described as "were-hyenas". Unfortunately, even as late as the 1970s, racial prejudice persisted in mainstream academic circles; either as a result of unreliable sources or a personal agenda, Gygax's original compendium and the scholarship that followed it perpetuate the same fear-mongering and sense of White moral superiority as St. Clair and Dunsany's stories: the gnolls are portrayed as savage, sadistic, and inherently chaotic, worshiping a demonic god named Yeenoghu that is completely unknown to indigenous spiritual traditions. Gygax even draws upon St. Clair's prose in his description of gnoll physiology, describing their eyes as blood-red just as she did (admittedly, given the popularity of red eyes as a mark of the demonic, this may be sheer coincidence).
Dissenting schools of thought do exist, and have attempted to rehabilitate the cult's image. St. Clair even offers a slim window for sympathy within her story: Mortensen's death occurs largely by accident, the tragic result of the arrogant European's insensitivity to local culture. Unfortunately, the cult itself is believed to have gone extinct some time during the former half of the Twentieth Century, and thus a truly accurate account of its history and beliefs may be impossible.
Particularly Thorvald with his mico-diatribe on the Gnoles 
