10 Worst Things Batman Did To Villains
3. Torturing Penguin - Batman: The Dark Knight #2
Penguin is one of the few Batman villains that seems to know when to answer Batman's questions - he may not be completely truthful, but he's often smart enough to reveal what he knows rather than take a beating.
The opposite was true in David Finch's Batman: The Dark Knight, in which Penguin wasn't overly cooperative. It seems that villain could not have picked a worse time to not answer Batman, as the dark knight was so desperate for answers that he immediately began breaking bones... then more bones.
It may not be quite on the same level as jamming sharpened sticks underneath someone's nails yet breaking each of a man's limbs is undoubtedly torture, and undoubtedly one of the worst things Batman has done to a villain.