The Cosmic Destroyer. This creature travels from solar system to solar system in search of planets that land in its goldilocks zone. Once it finds a suitable planet it opens up and latches onto said planet. Then proceeds to spew enough molten liquid from its throat to break open a hole beneath the planet's surface. From there it feeds on the life of the very planet itself. Once it has had its fill, and the planet becomes a cold space-rock, this monster abandons its meal in search for the next. It isn't evil per se, just apathetic to other life. Too big to care.