9) Superman: Red Son
There are a lot of great Superman stories out there which could be explored in an animated feature, but seeing as many of the most iconic tales have already been done, why not try adapting one set in an alternate reality? In the 1950s set Superman: Red Son, the young Kal-El crash landed in Russia and was brought up to be an agent of the Soviet Union.
Understandably, a superpowered alien under Soviet control caused panic in the United States, shifting the focus of the Cold War arms race from nuclear weapons to superhumans. What followed in the Mark Millar-penned story was a fascinating look at an alternate history which included new versions of Batman, Wonder Woman and more. The ending, meanwhile, offers up a particularly memorable twist.