Annihilus

Annihilus, nicknamed The Living Death That Walks, is a alien supervillain from Marvel Comics and a classic recurring enemy of the Fantastic Four. He later became a threat to the entire universe as the main villain of the cosmic storyline Annihilation where he commanded the Annihilation Wave.

Story
The being later known as Annihilus, was born from an incident involving a Group of tyrannian explorers on the planet Arthros in the Negative Zone. The tyrannians were forced to release the experimental spores they carried with them on the planet in order to save themselves.

Centuries later, the spores formed an insectoid being, smart but pretty weak. Luckily, the creature used the technology of the tyrannians to survive and build an exoskeleton for himself as well as discovering the powerful artifact known as the Cosmic Control Rod.

The creature, named himself Annihilus, soon became obsessed with Death and survival and that every sentient being is out to kill him or steal the Cosmic Control Rod from him. Driven by his paranoia, Annihilus conquered planet Arthros and many other planets in the Negative Zone.