As The Dark Knight continues to obliterate box office records, it can only be expected that Heath Ledger's performance will remain in the limelight for quite some time. In hopes that this sensation will increase interest in the source material, provided is a selection of acclaimed graphic novels. Having already previously discussed essential Batman works, the following highlights the Joker's tenure in print.
The Killing Joke

Story by Alan Moore
Illustrated by Brian Bolland
Cited on the cover as Tim Burton's favorite comic, this 1989 classic by Alan Moore is considered the definitive Joker story. Look here not only for the first Joker origin story, but the arch-nemeses' "madness theory" depicted in the The Dark Knight. This disturbing tale details the fatal relationship between Batman and the Joker, and concludes with an ambiguous ending that leaves one to wonder. Along with Arkham Asylum, this is one of the two books given to Heath Ledger when preparing for his role in The Dark Knight. Also look for more of Alan Moore's sensational work such as: V for Vendetta, The Watchmen and The League of Extraordinary Gentlemen.
Greatest Joker Stories Ever Told

This collection of 19 stories spans the Joker's presence in comics, including his shocking first appearance! Also look for the classic tale “The Joker's Five-Way Revenge.”
The Man Who Laughs

Story by Ed Brubaker
llustrated by Doug Manke
Taking place after the Joker's tragic accident, The Man Who Laughs introduces Batman to a type of criminal that will change him and Gotham City forever. Considered the sequel to Batman: Year One,in this tale the Joker "announces" his victims in a similar fashion to The Dark Knight. The title itself borrows from the 1928 silent film The Man Who Laughs, starring Conrad Veit which served as the direct inspiration for the Joker character.
Arkham Asylum: A Serious House on Serious Earth

Story by Grant Morrison
Illustrated by Dave McKean
In Arkham Asylum, comics legend Grant Morrison undertakes the psychosis of Batman's greatest rouges with overarching themes of sanity vs insanity, and the "inner-demons" that accompany the struggle. The second of two books given to Heath Ledger in his preparation for The Dark Knight, McKean's gothic artwork turns this story into an experience. Although, this one my not be for the faint of heart, as some of the panels are fairly graphic.
A Death in the Family

story by Jim Starlin
illustrated by Jim Aparo
One of the most tragic events in Batman history, as this story depicts the murder of the second Robin, Jason Todd, at the hands of the Joker. Though, with the Joker having gained diplomatic immunity through a strange loophole, how will Batman avenge his fallen partner? Check out this one to see how Batman history was changed forever.