Aetherii

The Aetherii (Or Ethereals) were formerly a Universal Dominating species that were even larger and more powerful than the Draconians. It was they who created the Triarii and their many brother-races, who were all devolved and placed on worlds when the Aetherii realised that the time of their Empire was drawing to a close. Several of these devolved races have become extinct, others have still not reachieved sentience

The Aetherii were eventually restricted to one known world and they were under the protection of the Triarian Collective, who were willing to fight to the death to defend their former master. Unfortunately, they were attacked and destroyed in the Great War, and while the Triarii were able to regain the world, they were not fast enough to save the Aetherii. A small amount of them (643) managed to escape in a single craft, and are currently well within Collective Space

The Universal Empire
The Aetherii once dominated the stars, deciding who lived and died on a whim. They decided the fates of countless worlds in their time and created races such as the Triarii for specific purposes.

Over time, the Aetherii grew more and more powerful, but as they did they attracted more attention. Slowly, they came to be hated for their arrogant demeaneur, and this would be part of what would drive the Void Humans to conflict with them.

Eventually, their time as the dominating race came to an end. The combined problems of the Darkness, the Plague and the Void Humans, as well as countless other races turning on the Aetherii, resulted in the collapse of their Empire. The Aetherii devolved their creations so that they might be untracked by those who would seek to destroy them, and then seeded them on their original home planets, allowing them to rise from the ashes

The Aetherii remained defiant, fighting to stop the offensive of the enemies despite knowing they could not. Eventually, the Aetherii were crippled beyond recovery and presumed extinct, although one small group had managed to hide on a planet and remain hidden from the eyes of the galaxy until recently

During the Great War, the Draconians attacked and destroyed the Aetherii Remenant on the Last Aetherii world, which proved to be a large mistake as the Collective quickly commited it's self to total war. When the world was reclaimed, all the Aetherii on it were dead, leaving just those who had escaped on a single ship

Technology
The Aetherii were once the most advanced race in the Universe, possessing technology unimaginable to almost all in the universe. This ranged from highly destructive weaponry to shields that can take insane damage as well as other more civic technologies. They incorperated Psionics into some of their technology as well and have genetic engineering surpassing any known. Despite this, they did not yield their technology to their chosen successors, prefering that the Triarii find most of their advancements themselves or reverse engineer Aetherii tech

Psionics
Their Psionic capability surpassed even that of the Triarii due to their heavy reliance on Psionics. Many of them used Psionics to keep themselves alive for Eons on end, which is just as well given they were almost extinct. They sayid that one day the Triarii will be as powerful as them, once they have proven themselves, but note that 'The day you finally ascend is far off'