Batman: Under the Red Hood (2010)
One of the all-time great Bat entries, Brandon Vietti's Under the Red Hood pits the Caped Crusader (Bruce Greenwood) against an eerily familiar vigilante (Jensen Ackles) who subscribes to a much more punishing moral code. At a tight 75 minutes, this animated flick weaves intricate backstories into a high-octane plot that explores the differences between stopping crime and controlling it. Amazo, Riddler, Ra's al Ghul, the Fearsome Hand of Four, and, of course, the Joker make appearances along the way.
You'll also be happy to know that HBO rolled out lots more Batman fare this month, including Tim Burton's two always watchable efforts, Joel Schumacher's two less watchable mid-'90s follow-ups, and several more 'toon specials.
Stream it on: HBO GO/NOW