Thanos

One of the most well-known supervillains thanks to the MCU, Thanos is what can be called a mutant Eternal, which makes him among the most powerful of his race. The fact that he has tangled with Death herself (of whom he is in love) made him even more powerful than before. The Mad Titan, even without the Infinity Gauntlet, has slapped Thor and Hulk as if they were second tier superheroes.

He is immortal and possesses all of the usual superpowers, including telepathy, teleportation, and so on.

However, he is best known for his search of mysterious and extremely powerful artifacts. The Infinity Gauntlet and its Infinity Stones are the best known – artifacts which, basically, bring him omnipotence and omniscience. Another artifact is the Heart of the Universe, which is even more powerful than the Infinity Gauntlet with all of the Infinity Stones, which makes the user the most powerful being in the Marvel comic book universe.

Thanos has possessed both of these artifacts at some point. Just by snapping his fingers, he was able to kill half of the universe. How many supervillains have managed that?