Fused Zamasu

When Goku Black (Zamasu inhabiting a stolen copy of Goku's body) and Future Zamasu (an immortal version of the same deity from Trunks' timeline) realize that Goku, Vegeta, and Trunks are becoming too strong to defeat individually, they use the Potara earrings to merge. The resulting Fused Zamasu possesses Goku Black's ever-growing Saiyan power combined with Future Zamasu's immortality, creating a being that should be truly invincible.

However, the fusion carries an inherent flaw. Because only one half of the fusion is immortal, Fused Zamasu's body begins to deteriorate during prolonged combat. His right side becomes grotesquely mutated, reflecting the conflict between mortal and immortal cells. Despite this instability, he proves nearly impossible to defeat. Vegito Blue manages to fight him on even terms but defuses prematurely. Trunks, channeling the energy and hope of humanity into his sword, manages to bisect Fused Zamasu, but the entity begins merging with the fabric of the universe itself, threatening all of existence. Only the intervention of Future Zeno, who erases the entire timeline, ends the threat permanently.

Fused Zamasu represents the most philosophically charged villain in Dragon Ball Super. His Zero Mortals Plan, the complete extermination of all mortal life, stems from a genuine belief that mortals are inherently sinful and that the gods have failed in their duty by allowing them to exist. This makes him a villain who believes he is the hero of his own story, a rarity in Dragon Ball where most antagonists are motivated by simple conquest or personal power.

The decision to resolve his arc through Zeno's timeline erasure is one of the boldest narrative choices in Dragon Ball history. Rather than having Goku defeat the villain through a new transformation or technique, the story acknowledges that some threats are simply too great for any individual warrior. The destruction of Future Trunks' timeline carries real emotional weight, as it wipes out the world that Trunks and Mai fought so desperately to protect.