A fitting ending for his kind, the hero remarked without compunction, as the adversary he just assaulted flailed toward a grisly demise into a vat of acid. This was, surprisingly, the Batman, at the conclusion of his first story—
The Case of the Chemical Syndicate—in Detective Comics #27 (May 1939). Granted, his foe, a murderous
rat named Stryker, certainly deserved a comeuppance, but Batman's action was shockingly excessive. By conventional standards, heroes do not kill.