The Lord of Talons, The Vulture King, Devil-Bird of DOOZA-THOM
The Great Old One appears as an enormous bird-like horror with blazing eyes and a savage beak lined with razor-sharp fangs. Its wings and body are covered with sharp black scale feathers, and it has a terrible, barbed dragon-like or serpentine tail. It's piercing screech can cut mountains in two and it drinks unfathomable amounts of blood. Curiously, the creature has one foot—legends say it lost the other in an earthshaking conflict with another, now forgotten, monster-god.
Groth-Golka's single talon is clutched firmly upon the hearts and minds of Dooza-Thom's civilization. The sweltering mesas and savannas of the kingdom are dotted with hundreds of monstrous statues of lizard-birds. Whether these grim effigies were crafted by an older civilization, or placed there more recently by the feather-cloaked shamans of Groth-Golka, is not known. Outside of the Duzamba, the Vulture King's most fervent followers are the vrock demons and harpies, though human cults are present across the world, if only in the shadows.
Groth-Golka is master and patron of all that flies. While this is a grandiose claim, it is far from unfounded arrogance. It is worshiped by a wide variety of evil flying creatures and demands propitiation by sacrifice with victims crucified on high peaks for the birds and elements.
"The moon was hidden by black, flapping shapes that circled and swooped like enormous fishing-birds, darting down to the altars to pluck and tear at the wriggling bodies bound there...and one of the huge, queerly deformed-looking bird-things emerged into the moonlight, and I stared with unbelieving horror at its hulking, horribly quasi-avian form, clothed with scales not feathers... one glimpse of the repulsive thing with its one leg and glaring Cyclopean eye and hideous, hooked, fang-lined beak..."—The Fishers From the Outside, Lin Carter
Groth-Golka is one of those bizarre entities I imagine CAS welcoming into his mythologies with open arms. It has a checkered past as a bird-monster slain in Robert E Howard's "Gods of Bal-Sagoth," To explain its defeat by mortal hands, this Groth-Golka was retconned as being a mere avatar. It reappears afterward in Lin Carter's "The Fishers From Outside"—with the wrong name. Subsequent reprints corrected Carter's goof. In his short story, Carter refers to Groth-Golka as the avian master of the eponymous Fishers, nightmare bird-things obliquely mentioned in HP Lovecraft's poem "The Outpost." In the Player's Guide to Xoth, author Morten Braten (Thusa) astutely picks up on the African connections and puts his ersatz Groth-Golka (Jul-Juggah, the Devil-Bird of Azimba) in charge of his pastiche (Howard's) Zembabweans (or rather L. Sprague de Camp and Carter's pterasaur-riding Zembabweans from "Red Moon of Zembabwei"). Even with that pedigree, not much ink on Groth-Golka has been put to paper. I picked up on the deities' "pteranodon-but not quite" countenance and connected it to the evil kaiju Gyaos, This blood-drinking reptavian bird monster also once lost a foot in battle, though I imagine Groth-Golka's famous "one leg" might be a less wholesome appendage. A few artists have tried to ratchet up the weird when drawing Groth-Golka, because birds aren't scary, apparently. But stand face-to-face with a monstrously huge bird? You'd shit your goddam pants.
Another obvious comparison and inspiration (and where I want to
focus going forward) is the demon Pazuzu. Made famous in "The Exorcst," where
Pazuzu's idol is depicted with the aforementioned appendage.
Before being honored in Hollywood, Pazuzu had a sky high profile
in ancient Mesopotamia as the patron of flying monsters and wind
demons, and has appeared in some form in nearly every
iteration of Dungeons & Dragons.