The man who trained Snake Eyes and Storm Shadow. He has died in every version of G.I. Joe he has appeared in, and Storm Shadow is always the reason why.
Hard Master was the leader of the Arashikage clan, under the influence of Snake Eyes, he decided to take the clan in a new direction away from their criminal roots, this decision angered his nephew Storm Shadow (this was the basic origin of the character, the Resolute and Renegades series offered different takes on his death that followed)
Death in Resolute: Storm Shadow was angry his uncle would not teach him the seventh step death blow, and more so that Hard Master intended to turn leadership of the Arashikage to the gaijin Snake Eyes, and in turn hired a COBRA sniper to kill Hard Master and his heirs, the sniper killed Hard Master and his daughter, but Snake Eyes survived.
Death in Renegades: Storm Shadow attempted to poison tea Snake Eyes was to drink, but Hard Master drank it instead. Storm Shadow later discovers he was responsible for his uncle's death, and confesses his sins to Snake Eyes and Jinx.