Tsathoggua (the Sleeper of N'kai) is a fictional supernatural entity in the Cthulhu Mythos shared fictional universe. He is the creation of Clark Ashton Smith and is part of his Hyperborean cycle.
Tsathoggua (or Zhothaqquah) is described as an Old One, a godlike being from the pantheon. He was invented in Smith's short story "The Tale of Satampra Zeiros", written in 1929 and published in the November 1931 issue of Weird Tales. His first appearance in print, however, was in H. P. Lovecraft's story "The Whisperer in Darkness", written in 1930 and published in the August 1931 Weird Tales.
Read more about Tsathoggua: Description, Family Tree, Other Appearances, The Tsathoggua Cycle