If I remember correctly (this sketch is from 2003) the four tentacled thing at the bottom left is a member of one of the alien races that populate Cthulhu Mythos stories. Unfortunately I’m not sure where my copy of the Encyclopedia Cthulhiana is at the moment and I haven’t been able to find a species in Cthulhu Mythos Wikipedia entries that seems to match so we’ll just have to leave the creature anonymous.