The DC Universe is filled with dangerous villains of all kinds, but there’s a number of foes so evil that Batmanhimself considers them completely irredeemable. Bruce Wayne’s no-kill rule comes from his traumatic experience in the infamous alley where the legend of the Batman was born. As a result, the Dark Knight has repeatedly discarded the idea of killing dangerous criminals like Ra’s al Ghul and Victor Zsasz, to mixed results.
Batman Officially Names DC’s 3 Most Evil Villains