The Tcho-Tcho are the main antagonists of the Cthulhu Mythos short story The Lair of the Star-Spawn by August Derleth and Mark Schorer. They are a tribe inhabiting the legendary Burmese city of Alaozar who worship the Great Old Ones and ritualistically kill and eat all humans who come too close to their city.
The Tcho-Tcho were spawned by the descendants of the Great Old One Chaugnar Faugn, having been genetically engineered by Zhar and Lloigor. Inhabiting Alaozar on the Plateau of Sung in Burma, the beings worshipped their progenitors Zhar, Lloigor and Chaugnar Faugn, as well as their relatives Hastur and Ithaqua, and Rhan-Tegoth, the Terror of the Hominids.
In about 1902, a scientific expedition lead by Eric Marsh came too close to Alaozar, and were slaughtered by the Tcho-Tcho, although Marsh survived, having broken rank, and reached Alaozar, where he was captured by the Tcho-Tcho. Inside Alaozar, he encountered the Chinese scientist Fo Lang, who had been enslaved by the Tcho-Tcho and forced to help them summon Zhar and Lloigor to unleash upon the world.
During a ritual, whilst the Tcho-Tcho bowed down to their high priest E-Poh and Lloigor, Fo Lan managed to astrally project himself and converse with the Elder Gods, the sworn enemies of the Great Old Ones, who told him to convince E-Poh to open the gates to the Great Old Ones, which would allow them to reach Alaozar. Fo Lang did so, and also convinced E-Poh to release him and Marsh to perform their own ritual. E-Poh did so, but had four guards escort them.
After reaching the Plateau of Sung, Marsh and Fo Lang easily overpowered and killed their guards, and watched as the Elder Gods descended and destroyed Alaozar, burying Zhar and Lloigor in the process and setting back the Great Old One's plans.