Beyonder

The puppeteer of Battleworld is the most powerful among all of Marvel’s supervillains. In the omniverse (the sum of multiverses), he is the embodiment of an entire multiverse – so he alone is millions times stronger than all the Marvel superheroes and supervillains combined. He is the sole responsible for the creation of Molecule Man.

When Owen opened the portal to the other dimension, he was infused with the power of the Cosmic Cube. However, most of that power escaped and gained sentience and curiosity – the Beyonder. So powerful this being was that, at one time, he killed Death (imagine how sad Thanos must have been), only to resurrect it afterwards.

His anger can be felt on a multiversal scale, which basically means that he can destroy multiverses with just his thought in an instant. Literally, he is like a biblical God – omnipotent, omniscient, omnipresent, omni-everything.