BmB said:
Big question; what mythical themes does it reflect? This is a big part of star wars, however terribly the prequels handled the jesus/oedipus myths.
I'm not up on my "mythical theme vocab" so I won't give you a nice concise name for it, but it's that overwhelming, foreign, unstoppable force that seeks to destroy you physically or perhaps just your way of life. Having them be slightly non-human is always a perk. See: zombies, zealots, undead armies, biowarfare, etc.