Zeno

is a former member of the Ten Commandments, who fought in the great war against the other four races 3,000 years ago.

3,000 years ago
Three thousand years ago, the Ten Commandments fought for their race against the other four races in the great, ancient Holy War. The Ten Commandments at that time were led by Meliodas until he ended up betraying them, killing two of its members, Aranak and Zeno, in the process that would later be replaced by Drole and Gloxinia.