While his story arc could have been better, I did like Goku Black as a character. Looking like Goku, this evil being had almost destroyed everyone on Earth in Future Trunks’ timeline.
I always figured he wasn’t really Goku. Even Lord Beerus and Whis figure that one out pretty quickly.
Turns out his name is really Zamasu. He is a kai in training to be the Supreme Kai. He planned to murder his master in a goal to wipe out all mortals in the Multiverse.
Unfortunately for the Z Warriors, Goku Black is also helped by another reality version of Zamasu who is indestructible.
When he starts losing, the two beings fuse into one. At the horror of two Supreme Kai’s watching the battle, as the fusion is very taboo.
Future Trunks manages to get the last blow and end his life as he knew it.
I didn’t like how his energy still stayed around after death. Which forced Goku to summon Future Zeno to erase him from existence.