Annihilus
Species: Arthrosian
Enemies: Fantastic Four, The Avengers, Thor
Annihilus is often forgotten about due to other characters being used more prominently over the last few decades. Yet initially, there was never a galactic threat quite like Annihilus. In most uses, he has been the ruler of “The Negative Zone.” This is an antimatter universe that exists outside of our own. While Annihilus remaining there is not really a problem of our concern, he could do a lot of damage if he made his way into our universe. When Reed Richards of the Fantastic Four finds out a way to travel to and from this universe, he takes advantage.
Yet that puts us all at risk for if Annihilus escapes the Negative Zone, we’re all in trouble. Known as “the living death that walks,” he is to be feared by any and all. What makes him the most powerful is his Cosmic Control Rod. It allows him to manipulate cosmic energy to control the molecular structure of matter. It can even project massive energy and concussive force. Of course, long-term exposure to the rod can slow the aging process of the wielder, allowing Annihilus to become essentially immortal. This is why he is one of the most powerful galactic characters in comics.