Xantirians

The Xantirian Empire were a Kardashev Type III civilization which inhabited Kepler-186f millions of years before the start of humanity. They were driven to extinction by Emanuel Fialik.

Connection to Emanuel Fialik
Emanuel Fialik visited the Xantirian Empire's homeworld, Kepler-186f by invading a colonial space vessel from an unknown world. While they were colonizing the planet, the larval-form Fialik crawled on to the ship and hid until the vessel returned to Kepler-186f.

Once Fialik boarded Kepler-186f, it began to kill. Fialik killed (presumably) anywhere from 3,000 to 9,000 Xantirians and used their souls to begin its hibernation phase, which lasted 75 years. Once Fialik emerged with its new body, it incorporated itself into Xantirian society. It slowly made connections to the Xantirians and gained the trust of a select few members of their civilization.

In much the same way that Emanuel Fialik tried to manipulate Rammstein here on Earth to capture as many human souls through their music as possible, Fialik was able to influence the soul absorption of an estimated three-trillion Xantirians, driving the entire species to total extinction. After a while, all signs of their civilization crumbled to dust, leaving Kepler-186f looking barren.

Biology
Much of the Xantirians' biology is unknown. It has been theorized that Xantirians all had a collectively identical taste in music, as Emanuel Fialik was able to exterminate the entire species. This musical taste would most certainly have been derived from biological / genetic factors.

Technology
The Xantirian Empire wielded technology which is many orders of magnitude more advanced than human technology. The Xantirians had mastered teleportation, cloning, terraforming, and subatomic particle manipulation. It has been hypothesized that the Xantirians were the precursors to humanity in some way, but this cannot be reliably confirmed.

Within the arsenal of the Xantirian Empire was the Type VII Invader Mothership, which Emanuel Fialik used to traverse a small patch of the universe for a few million years before reaching the Earth. Alongside the Type VII Invader Mothership, the Xantirians also created many specialized forms of colonial space-travelling vessels which were used for terraforming and city construction.