H.P.Lovecraft's Dreamlands Wiki

Atlach-Nacha in Eldritch Horror: The Dreamlands

Atlach-Nacha is a Great Old One and god of spiders. Atlach-Nacha appears as a giant spider with a human-like face, and on rare occasion as a beautiful, multi-armed woman. It dwells in a cave system beneath Mount Voormithadreth. There, it spins a great web, forming a great bridge between the Dreamlands and the waking world. It is believed that when the web is complete, the end of the world will come.

Atlach-Nacha was said to have come to Earth from Saturn along with Tsathoggua; in other version of the myth, the spider god spun a web between the two planets that allowed Tsathoggua to arrive.

A few cults devoted to Atlach-Nacha have existed at various times. The Phoenicians held this Great Old One in reverence, and small groups of worshipers are known to have existed in India and the Andaman Islands. The Esoteric Order of Dagon speaks of Atlach-Nacha as a being who dwells on a "Tree of Death" and punishes those who do not breed with the deep ones and each other. Atlach-Nacha deals mostly with sorcerers who contact it in exchange for arcane knowledge and visions of other dimensions.

Spiders of Leng are thought to be the children of Atlach-Nacha.