“Gnolls: A cross between Gnomes and Trolls (. . . perhaps, Lord Sunsany (sic) did not really make it all that clear) with +2 morale. Otherwise they are similar to Hobgoblins, although the Gnoll king and his bodyguard of from 1-4 will fight as Trolls but lack regenerative power.” (Dungeons & Dragons, Volume 2: Monsters & Treasure, Tactical Studies Rules, 1974; Greg Bell illustration)
As he noted, Gary Gygax borrowed the name “gnole” from a story by the Anglo-Irish writer Lord Dunsany. The “cross between Gnomes and Trolls” detail was entirely a product of Gygax’s imagination, based solely on the appearance of his spelling of the name.  When he rewrote the monster descriptions for AD&D he kept the name but gave them a new identity as hyena-men.
Lord Dunsany’s “How Nuth Would Have Practised His Art upon the Gnoles” first appeared in The Book of Wonder in 1912. He did not describe his gnoles beyond being a very dangerous sort of woodland creature that kept large emeralds. An illustration showed shadowy ape-like shapes.
Margaret St. Clair wrote more about Dunsany’s gnoles in her story “The Man Who Sold Rope to the Gnoles,” in The Magazine of Fantasy and Science Fiction, V2 N5, October 1951, under the pseudonym Idris Seabright. She described gnoles as lumpy (”a little like a Jerusalem artichoke made of India rubber”) and with tentacles, repeating Dunsany’s details about having emeralds in their homes and their habit of hiding in holes in tree trunks. Gygax acknowledged both St. Clair and Lord Dunsany as inspirations in Appendix N of the AD&D Dungeon Masters Guide.
