10 Times Batman Went Too Far
10. Killed A LOT Of People - Early Detective Comics
Batman, first and foremost, is not a killer. Bruce is fully aware of how close to the edge he is of becoming just like the criminals he fights, so he sets the hard rule for himself that he will never resort to murder to achieve his goals, no matter how noble the goal, or how justified the killing.
I imagine if you told this to Bob Kane and Bill Finger, they'd look at you like there were lobsters crawling out of your nose.
During his first years, Batman killed a LOT of criminals, even straight up carrying a gun on his person. He was a much harsher, hard boiled detective-type character you'd typically see in film noir, with all of the violent moral grey areas that implies. Only difference is that the detective in this story wears a rubber bat suit.
Subsequent Batman stories pretty much pretend that this never happened, and with all of the DC universe's reboots, it basically didn't. They DID try to reference it in Batman Odyssey. But we don't talk about Batman Odyssey.
Ever.