Originally Posted by Crack

Cthulhu is a giant fictional being, one of the Great Old Ones in H.P. Lovecraft's Cthulhu Mythos. It is often cited for the extreme descriptions given of its appearance, size, and the abject terror that it invokes. Because of this reputation, Cthulhu is often referred to in science fiction and fantasy circles as a tongue-in-cheek shorthand for extreme horror or evil.