Courtesy of RPGMaker MV's demo (MV being the most recent version of RPGMaker), one of the most genuinely horrifying demons you're ever likely to see:
What's amazing about this is that it's described only with the generic moniker "demon." It's not "parasitoid demon" or "wearing-a-hapless-angel-as-a-tail-ornament demon." It's just "demon."
I'm kind of iffy on a lot of MV's creature art in terms of art style, but I actually really like the design aesthetic it brings to the table; it's probably the most imaginative art in any of the RPGMakers.