The Treader of the Dust

"...The olden wizards knew him, and named him Quachil Uttaus. Seldom is he revealed; for he dwelleth beyond the outermost circle, in the dark limbo of unsphered time and space. Dreadful is the word that calleth him, through the word be unspoken save in thought; For Quachil Uttaus is the ultimate corruption; and the instant of his coming is like the passage of many ages; and neither flesh nor stone may abide his treading, but all things crumble beneath it atom from atom. And for this, some have called him the Treader of the Dust."

-The Treader of the Dust, by Clark Ashton Smith