Annihilus (Earth-21399)

"What good is life to the universe? And for that matter, what good is the universe to life? Ours is an existence as empty as the blackening skies, and I believe the universe has had enough of it. But you worms just won't accept that, won't you? You fail to understand... I come to you with good tidings. I give you a parting gift from existence. I give you... ''annihilation."

- Annihilus

Origins
The being that would later call itself Annihilus is a reptilian being who hatched alone on the planet Arthos, a desolate and nearly lifeless world in the antimatter universe known as the Negative Zone. Though barren, Arthos was host to the ruins of an ancient alien civilization, and the hatchling used them as shelter from the violent Arthosian weather, all the while feeding on the trace colonies of algae and native insects.

At some point, the hatchling began to question his place in the world and ventured into the Arthosian ruins, seeking answers. Once there, he discovered a secret research lab that seemed to center around a mysterious rod that had no initial effect. As the hatchling began to move on, however, the rod suddenly started to glow and sputter. Entranced by the sight, the hatchling stood there as the rod exploded in a burst of energy, infusing him with cosmic power.

The infusion of cosmic energy not only granted the hatchling great power, but enhanced his intelligence. However, the knowledge revealed to the hatchling was so terrible that he went mad from the revelation. Adopting a cruelly nihilistic worldview, the hatchling made it his mission to speed up the progression of entropy in the Negative Zone – to cleanse it of the very existence he regarded as futile and meaningless.

Annihilation Wave
Dubbing itself Annihilus, the hatchling mastered the technology he found in the ruins, using the genetic engineering labs to create a loyal army of drones that he controlled mentally and building a massive space station/dreadnought called the Harvester. He dubbed this army the Annihilation Wave and set out from Arthos on his nihilistic crusade.

Every time Annihilus found a planet that contained life, he would commit a complete and thorough genocide on all living things there. Sometimes, he personally oversaw and even partook in these killings. On the first day of the crusade, known as Annihilation Day, the Wave destroyed twelve inhabited worlds.