Kepler-186f

Kepler-186f is an exoplanet which is located approximately 580 lightyears away from Earth. It was once the homeworld of the Xantirians, a Kardashev Type III civilization which was singlehandedly exterminated from the inside by Emanuel Fialik.

Connection to Emanuel Fialik
Long before complex life began on Earth, the planet was invaded by Emanuel Fialik. At an unknown point in time, Fialik secretly boarded a colonial vessel from an unknown world while in larval form, and left the vessel once it boarded on Kepler-186f. It immediately began harvesting Xantirian souls (which were in heavy abundance at the time, due to their success as a species), and shortly thereafter, began a 75-year hibernation period in the core of the planet.

When it emerged from the planet's core, it overtook the entire species in less than 10,000 years; slowly absorbing all of the Xantirians' souls through the use of Xantirian music. Shortly afterwards, Fialik left the world on a stolen Type VII Invader Mothership, and over millions of years, all evidence of the Xantirian empire began to decay.

The stolen Type VII Invader Mothership was used to reach Earth.