Ubbo-Sathla (nickname: the Unbegotten Source) is a fictional character, one of the Outer Gods in the pantheon of H. P. Lovecraft's Cthulhu Mythos, described as a black formless mass resting in a grotto deep beneath the frozen earth. Ubbo-Sathla is said to have spawned the prototypes of all forms of life; now it is said that wherever his pseudopods touch is forever devoid of life.

"There, in the gray beginning of Earth, the formless mass that was Ubbo-Sathla reposed amid the slime and the vapors. Headless, without organs or members, it sloughed off from its oozy sides, in a slow, ceaseless wave, the amoebic forms that were the archetypes of earthly life. [About it] there lay the mighty tablets of star-quarried stone that were writ with the inconceivable wisdom of the premundane gods." -- Clark Ashton Smith, Ubbo-Sathla