SrJoben: They're clearly The Shadows from Babylon 5. Which in turn are a pastiche of the forces of Mordor from LOTR. :P
lol I think it's clear that most space opera is heavily derivative.
Apathy1989: While I agree space opera can be derivative (like any fiction), I think the shivans and reapers both are just copies of Babylon 5's Shadows. The religious tones, insect bodies and countless cycles of extinction make it feel very similar.
Only problem with that theory is that the Shadows had a very set philosophy -strength through conflict- which is polar opposite that of the Vorlons.
The Shivans have no such philosophy or motives, and it's been hinted at by official sources that the Shivans are a constructed race, rather than an evolutionary one like the Shadows.