Gnolls are savage, hyena-like humanoids who roam grasslands preying on anything weaker than themselves. Barbaric and filled with bloodlust, they are known to be prominent demon-worshipers, honoring the fiend Yeenoghu in their brutal faith.
Gnolls are usually between seven and eight feet tall, weighing around 250 to 320 pounds. Their whole bodies are covered in reddish-brown fur which becomes shorter as it surrounds their faces and clawed hands to reveal grey colored skin. Their pelts vary from mono-colored to spotted and their eyes are either yellow or black. They use primitive equipment made of horn, metal, or leather.
Gnolls first appear in the OD&D White Box, being described as, perhaps, a "cross between a gnome and a troll." They have high morale, and their elite members fight "as Trolls," but without regeneration.
When they next appeared, in the 1e Monster Manual, the pun was replaced with the idea of demon-worshiping hyena-people, and it has stuck.