A shoggoth (occasionally shaggoth) is a monster in the Cthulhu Mythos. The being was mentioned in passing in sonnet XX ("Night-Gaunts") of H.P. Lovecraft's sonnet cycle Fungi from Yuggoth, written in 1929–30, and were expounded upon in his novella At the Mountains of Madness (1931).
Read more about Shoggoth: Description, Other Appearances