ColonelHardisson
What? Me Worry?
The first time I recall seeing the cooshee was when it was introduced into AD&D in module S4, Lost Caverns of Tsojcanth, from 1982. That module a had a booklet of new monsters, spells, and items. Among the monsters it introduced were Valley Elves, Graz'zt, Fraz Uurb'Luu (or however you spell it), bodaks, chasme, fomorians, gorgimeras, pech, and Kostchtchie (or, again, however you spell it).