During a rebellion fought on his home planet, he was on the side fighting the rebellion. He wiped out hundreds of rebels just on his own, and I need some sort of nickname for him. Kind of like "Jack the Ripper", but obviously not a name that's already been used for something else. If you have any fun ideas feel free to share!
PS
His "species" is kind of like robots. He used an electric spear during the rebellion, which fried the inner workings of the victim, resulting in their "death". I hope that provides some context.