What is the name of the final boss in Final Fantasy IV?

The final boss in Final Fantasy IV is Zeromus. The party faces this embodiment of hatred in the core of the Moon after defeating the game’s apparent mastermind, Zemus.

Zemus is a Lunarian who manipulates Golbez and seeks to destroy life on the Blue Planet. When Cecil’s allies confront him, Golbez and Fusoya defeat Zemus’s physical form, but his hatred transforms into the far more powerful Zeromus.

The battle is shaped by a story-wide act of solidarity. Back on Earth, the people Cecil met during his journey pray for the party, giving Cecil and his companions the strength needed to challenge Zeromus. The Crystal also reveals Zeromus’s true form before the decisive fight.

Scarmiglione is one of the Four Fiends encountered much earlier, while Golbez is the principal antagonist for much of the story and not the final boss. Kain is Cecil’s ally and a playable Dragoon, so neither belongs as the game’s final enemy.