9. And At The End Of The Killing Joke
An accepted fan rumour for years, the "real" ending of Alan Moore and Brian Bolland's seminal Joker story The Killing Joke saw a resurgence in popularity recently when feted writer Grant Morrison brought it up.
During an interview on director/fanboy/occasional comic writer Kevin Smith's Fatman on Batman podcast, Morrison laid out what he saw as the only reasonable interpretation of the story's final panels.
Most people assume that, having put each other through the ringer, the lifelong adversaries dropped their eternal battle for a second and share a giggle. More than a giggle, even, as they each laugh hysterically and Batman has to steady himself on the Joker's shoulders, as seen in silhouette. According to the Morrison interpretation, however, that penultimate panel is far more sinister...
It instead shows the Dark Knight strangling his enemy, this story which saw him cripple Barbara Gordon and attempt to drive Commissioner Gordon insane being the straw that broke the camel's back. Finally, the end of the debate over why Batman doesn't just kill The Joker, since it's clearly the only way to stop him.
Of course, not all the events of the Killing Joke were carried over into the Batman mythos. Barbara did remain crippled until the recent New 52 rejig of the DC Universe, but you can't kill off The Joker. He's the best character! Or at least, you can bring him back without explanation.