I've seen this picture before, and I want to say it was in Sandy Peterson's Field Guide to Cthulhu Monsters. I won't swear to it, though. Without much research, I think this artwork shows Shub Niggurath, she who is known as the Goat with a Thousand Young. Question: why do many of the humans in such depictions carry pistols? I think I'd rather have a machine gun. The guy hiding behind the tree best represents what I would do.
