Batman: The Killing Joke is set to come out in 2016. In a blog post by DC Comics, Tim Beedle stated that “For years, it’s been one of the most regularly requested animated films by fans.” It will be produced by Bruce Timm (Batman: The Animated Series, Justice League) and will include a 15-minute prologue.
Two other animated films were also announced at Comic-Con. Batman: Bad Blood will be an original story introducing Batwoman, and Justice League vs. Titans is another original story featuring the Teen Titans.
The Killing Joke, released in 1988, was one of the darkest graphic novels of its time. It dealt with the paralyzation of Barbara Gordon, and was also seminal in how it showed a genuine interplay between Batman and the Joker. It was also implied that Batman finally snapped and that the Joker finally broke him.
Here’s a great conversation about The Killing Joke between Kevin Smith and writer Grant Morrison.