6. The Killing Joke (by Alan Moore)
The Killing Joke is perhaps one of the most critically acclaimed Batman stories of all time. Written by comic book messiah Alan Moore, The Killing Joke was originally a simple one-shot, but was met with such acclaim that it shaped continuity in almost every Batman comic after it. For me, its one of the greatest Joker stories, in which the Clown Prince commits one of the most heinous and singularly violent acts that Ive ever seen him commit (and Ive read a lot). Usually, Joker schemes and plots, but in The Killing Joke, he walks straight up to Barbara Gordons (Commissioner Gordons daughter) apartment and shoots her in the stomach, severing her spinal column and rendering her paraplegic. This book sets the stage for some serious psychological analysis of the Joker and was one of the first handful of books to do so with such weight that it changed the nature of the entire character into something more Ledger than Nicholson. It was also one of the first books to look at Jokers origin proper, to examine what made him in the cold light of day. Its common knowledge that Ledger read as much as he could in the lead up to playing the part; if you think The Killing Joke wasnt top of his reading list, then you clearly havent read it.