Batman: The Killing Joke is a graphic novel written by Alan Moore and illustrated by Brian Bolland. It is considered one of the definitive Batman stories and explores the complex relationship between Batman and his arch-nemesis, the Joker. The Killing Joke delves into the Joker's origin story and examines the thin line between sanity and madness. With its dark and psychological themes, stunning artwork, and iconic moments, Batman: The Killing Joke has left a lasting impact on the Batman mythos and the comic book industry as a whole.