Nephilim (Wing Commander)

The Nephilim are an insectoid race that are natives of an empire near the galactic core.

Existence by other races
The only race who knew of the Nephilim's existence were the Kilrathi, who had predicted their arrival in the known galaxy for centuries. Thousands of years before, Sivar, the Kilrathi God of War, had appeared to the first Priestess of Kilrah and he set in motion a prophecy that would predict the doom that would rain down on the galaxy.

"There shall come a time when one who has the heart of a Kilrathi, but is not Kilrathi born, shall rain cleansing fire down upon us. And Kn'thrak, a time of great darkness, shall embrace us.

Death itself shall pour forth, obscuring the stars in a veil of darkness. Theirs is the claw that tears flesh from bone.

Theirs is the poisoned fang.

Their numbers shall rend the universe barren and crush the breath from our clans. We shall be bathed in our own blood and rotted flesh shall be our fare. With a deafening thunder shall the dark age begin."

Kn'thrak (which takes place in the City of Ember movie universe)
In September 2416, Kn'thrak made itself apparent to the inhabitants of the galaxy. Moments after Lina Mayfleet and Doon Harrow first emerged from the dying underground city of Ember, an alien wormhole emerged and a massive warship appeared. The ship then opened up to reveal a massive plasma gun targeted at the decimated Earth. The alien vessel fired upon the planet, killing everyone on the surface, including Lina and Doon. A final blast then shattered the planet into billions of fragments.

Soon enough, dozens of mysterious warships entered the Sol system through the wormhole, setting the stages for an invasion of the galaxy.

Within the following weeks, several Kilrathi colonies, warships and space stations were destroyed by the Nephilim, as well as the majority of the forces sent by other races to investigate the attacks. Virtually no one survived these attacks, so all races remained mystified as to what these attackers were and what they planned.