10 Worst Things Batman Did To Villains
4. Kicking A Guy Into A Vat Of Acid - Detective Comics #27
How early Batman was never mistaken for a supervillain, I will never know.
In this instance, Batman punches a killer with such force that the criminal crashes through a metal barrier and falls into a vat of acid.
Going through a metal barrier would be painful enough, but then having one's entire body covered in industrial grade acid? Ouch.
Once again though, Batman sees his efforts as completely reasonable, declaring this a "fitting end for his kind" - which is rather ironic seeing as the guy he threw into the acid had planned to do the same to his intended victim, making the supposed hero no better than the villain.
This definitely killed the guy as well, but not before he suffered some intense pain, of course.