"Batman: The Killing Joke" is one of the most highly anticipated "Batman" animated films given that it is based on "The Killing Joke" graphic novel by Alan Moore and Brian Bolland. As reported by Heroic Hollywood, Warner Bros. Animation have since released a special preview giving fans their first good look at the film.

The preview clip showcases actors Kevin Conroy and Mark Hamill reprising their roles as Batman and the Joker respectively, while also confirming Tara Strong as the voice of Barbara Gordon a.k.a. Batgirl and Ray Wise as Commissioner James Gordon. 

Producer Bruce Timm, who has worked on the "Batman: The Animated Series" and most of the DC Animated films, reveals that the movie may still get a PG-13 rating despite adapting just about every aspect of the original graphic novel, although there is still a chance the film will be given an R rating due to its dark and mature themes. 

Director Sam Liu also explains in the clip that the film will further explore the similarities and differences between the Batman and the Joker and how both have a tragic origin but managed to go down on very different paths in life. He also confirms that while Alan Moore stated the graphic novel is not within the regular "Batman" comics, this story has already been considered cannon by most fans. 

Actor Mark Hamill also confirmed that this is likely the darkest version of the Joker that he has ever portrayed, stating, "If people want to see a really nasty, vile Joker, this is the one."

"Batman: The Killing Joke" has not yet been given an official release date but according to the report, the film will make its world premiere at this year's San Diego Comic-Con, with a summer release date for home video and streaming likely to follow.