Goku Black is originally Zamasu, the North Kai of Universe 10, who traveled through an alternate timeline and gathered the Super Dragon Balls to make a wish to trade bodies with Goku. When his wish become true, he goes on to kill those important to Goku, in line with his plan called “Project Zero Mortals”.
This plan is to kill all mortals who he believed were a mistake in the divine creation, but the gods are too afraid to admit such mistake. Due to this belief, he thinks that killing all the mortals will be a way to serve “justice”.
Goku Black is ruthless, aggressive, and unhinged and he is ready to do everything to achieve his goal. At the end, he ends up being defeated and killed by Future Trunks.
