11 Comic Book Movie Characters Who Were Killed Way Too Quickly
2. The Joker
This could really cover both Batman franchises since the sad death of Heath Ledger basically meant the death of his character (as a mark of respect, inevitably), but it was Tim Burton's decision to drop his Joker off a building that should be deemed the bigger crime.
Burton's vision for the movie universe might have been perfectly pitched, but the decision to kill Batman's single most enduring villain in the first movie of what was initially planned to at least be a trilogy (and which would inevitably be stretched out further on the back of success) was a short-sighted mistake that would later bite Joel Schumacher hard.
Without The Joker as a continued malignant presence, the initial Batman franchise had to rely on increasingly poorer villain choices (though still mostly engaging in their own right), and the haunting spectre of the character also fatally meant that Schumacher tried in vain to recapture his spirit in further sequels.
There is more of The Joker's anarchy in The Riddler than in the comics, and Two-Face is the clown prince of crime in a different suit, and then with Batman & Robin, the director just went for silliness without the foundation of the character to ground it.
And the result was Mr Freeze.