Editing Future Zamasu (section)

=== Background ===
Future Zamasu existed within the timeline of Future Trunks. He was originally a Supreme Kai apprentice, studying under Future Gowasu. When Goku Black first encounters him, he insinuates that Future Zamasu harbored similar ambitions of becoming a Supreme Kai and eliminating Future Gowasu, referencing the latter’s fate by saying, "You also wanted to do this, right?", just after killing Gowasu himself.

On a fateful day, while serving tea to Future Gowasu, Zamasu from an alternate timeline appeared and killed Gowasu. This Zamasu revealed that he was searching for a timeline and universe devoid of a God of Destruction, as Supreme Kais are restricted from directly interfering with planets. His quest led him to Future Zamasu’s universe where Universe 7's God of Destruction, Future Beerus, was deceased. Zamasu from the alternate timeline offered Future Zamasu a chance to enact the "justice" he believed the universe deserved, and Future Zamasu accepted. Together, they used the Super Dragon Balls to grant Future Zamasu immortality and then destroyed the Dragon Balls to prevent anyone from reversing their wishes.

With no opposition left, the two Zamasus began their plan to eradicate "sinful mortals" and "unnecessary gods," aiming to create a "utopia" across all of existence. They started by killing all the Supreme Kais, which indirectly led to the deaths of the Gods of Destruction. Future Zamasu watched as Zamasu from the alternate timeline decimated countless planets, systematically exterminating as many mortals as possible.