The Grippli is a monster from AD&D. My information comes from the 1996 printing of the Monstrous Manual, and my own personal experience DMing the creatures.
Grippli 2 and 1/2 feet tall, and resemble tree frogs. they weigh 25 to 30 pounds and have human-like hands. Their grey-green skin offers natural camouflage in their preferred tropical environment. Grippli skin looks wet and shiny, but is actually dry to the touch. With their dexterous hands, Grippli can climb anything but sheer rock surfaces at the same speed they can run on the ground. Grippli eat fruit and insects. Grippli are rare, because, though they live to be 700 years old, they give birth only about six times in their life. Because of this, they defend their young ferociously.
Grippli are intellingent, and have established a primitive culture. Grippli generally build small wood and mud huts on the ground, in the shadow of large trees. On rare occasions, a grippli village may be found in the tree itself. A Grippli village generally contains between 10 and 70 inhabitants.
Grippli are intelligent enough to learn new devices and weapons very quickly, however, they have no desire to create these themselves. Instead, they trade rare fruits and other jungle specimens for them with groups of elves, or good humans.
A Grippli village is led by a tribe mother, who, along with being more than four feet tall, may emit a corrosive musk cloud. The tribe mother has 1 to 3 mates of abnormally large size that defend her against predators. The home of the tribe mother doubles as a temple to the Grippli's frog-like deity. Other deities in their pantheon of gods include evil snake gods, and spider goddesses.
Grippli, though diminuitve, can present a strong threat to a low to mid-level party. Even heavily armored warriors are threatened by them due to their speed. Grippli are fond of ambush attacks, and because of their natural camouflage and ability to move silently, they are quite skilled at setting one. Adventurers may not realize that an area is inhabited by Grippli until they are trapped in their snares and nets, and the creatures are hurling darts at them.