Shadow (and a few of the quotations you've provided) bring to mind the concept of "shades" in the ancient underworld: http://www.phatnav.com/wiki/wiki.phtml?title=Hades http://ancienthistory.about.com/library/weekly/aa081500a.htm http://homepage.mac.com/cparada/GML/Underworldmap.html Thanatoids??