04. The Killing Joke
Canonical Alan Moore one-shot about Joker's attempts to drive the Gotham Commissioner James Gordon completely bonkers. In typical Moore fashion there is an underlying political subtext and is one of the first attempts to humanise Joker by detailing his transformation from friendly, loving husband and father to be into the clown prince of crime. Moore also tries to make the point that Batman is every bit as demented and insane as the criminals he chases - a theory probably not too far from the truth, especially in the closing frames where Batman and Joker actually share a laugh, before the Dark Knight regains his composure. This utterly insane comic is most famous for the shooting of the former Bat Girl, Barbara Gordon who is left paralysed by a bullet to the spine in truly grizzly fashion.