"This common misconception stems from the hoax edition of the Necronomicon edited by “Simon.” The bulk of this book is supposedly based on Sumerian and Babylonian mythology and claims that Lovecraft drew on similar sources when he created his pseudo-mythology. It makes comparisons between Lovecraft’s creatures and figures in Sumerian mythology:
Lovecraft Sumer Cthulhu Ctha-lu, Kutulu Azathoth Azag-thoth Shub-Niggurath Shub Ishniggarab
These comparisons are especially tenuous, since none of these things exist in Sumerian or Babylonian mythology! Referring to any good text on either mythology demonstrates this. In addition, suggesting that Lovecraft had to lift these names from an existing mythology both goes against his habit of creating entirely non-human names for his creatures and diminishes the quality of his imagination."