Pyralis

 were an ancient race. They were imprisoned in dimensionally transcendental prisons. One such device was found by the Myriad crew, in the constellation of Kasterborous. On their release, they destroyed the moon and were non-corporeal beings of white light. Romana described them as following "The Pyralis are a race of phontonic mimics, energy beings with the power to adapt to almost any environment, they use this ability to seed themselves on an alien world, first learning how to impersonate the natives, and then mounting a devastating invasion. They're essentially parasites, creatures that exist purely to conquer others. The Pryralis once spanned the entire Kasterborous constellation but they were defeated after a century long war with another race. They were imprisoned within a temporal void, where they festered for thousands of years. Their prison gates have remained dormant scattered on innumerable worlds scattered around this part of the galaxy. Now with one of their gates opened, they are free to spill out into this universe. We must find a way to constrain them."