Board Thread:Other games/@comment-98.17.4.73-20150628002314

Another possible origin could be from a Love Craft work. Chthulhu is in later games (though his name was given to another monster (Malachi is Cthulhu yet, another big demon is called Cthulhu (in SotN I think it may have been renamed in other versions)).

Shadow Over Innsmouth I think is the story.

Though, due to them being in earlier games I think the Gillman thing is more likely, but thought I'd share this theory. 