1. Madness Is Like Gravity
After the chaotic events of The Dark Knight, Batman has finally apprehended Joker - but as ever, Joker has the last laugh, revealing his grander plan to take Harvey Dent and "bring him down to our level" was a success, and ultimately forcing Batman to take the fall for Dent's crimes. Joker explains that madness is like gravity, and that all it takes is a little push to turn a man insane, as illustrated by Dent's transformation. This is reminiscent of graphic novel The Killing Joke, where Joker attempts to prove anyone can be driven insane by torturing Jim Gordon. He also quips that he and Batman are "destined to do this forever" - that Batman won't kill him because of "some misplaced sense of self-righteousness" and that he won't kill Batman because he's too much fun - perfectly encapsulating the relationship between the two characters. As Joker dangles on the cable, cackling in the night sky, we see how hollow Batman's victory is. The Dark Knight is a complex look at heroes and villains, so it's only fitting the film should end in a less-than clear-cut fashion. Even if Heath Ledger's untimely death hadn't ruled out Joker's return in The Dark Knight Rises, this was a great way to see the character off - hinting that the unstoppable force and immovable object were destined to meet again someday. In fact, Joker's absence from TDKR is better, allowing viewers to make their own mind up on the whereabouts of the nefarious villain, no doubt plotting his next step in an endless battle with the Batman.