7. Emperor Joker
This entry is probably going to raise a few eyebrows because of how out of place it will seem, but I actually think it would be a perfect fit for these DC Universe Original Animated Movies. Perhaps one of Jeph Loeb's lesser known storylines, Emperor Joker sees the Clown Prince gain Mxyzptlk's powers after the imp unwisely gives him a portion of it to cause Superman some trouble. Joker, instead, manages to steal all of Mxyzptlk's power and changes the world in his image. He turns the heroes into poor caricatures of themselves, makes Lois Lane his queen, Luthor his jester and every night kills Batman only to resurrect him the next day and kill him again in a new gruesome fashion. It's up to Superman to help the heroes remember who they were and put the world back to the way it was. It is rare you see Superman go up against one of Batman's rogues outside of a Batman/Superman title, but if there is one villain who could handle their own against Superman, its Joker. That may seem silly to say, but watch how Joker nearly kills Superman in the first Batman/Superman crossover of the DC Animated Universe, 'World's Finest', and you'll know what I mean. The fact he has a wide array of powers at his disposal makes this fight fun and unpredictable. One of the best aspects of this story though is how it examines the Batman/Joker relationship through Superman's eyes, ultimately using a well known truth of said relationship to save the day. Emperor Joker is a little weird and out there, but would make for a fun and entertaining film.