In "The Dark Knight", the Joker is not a powerful villain. The reason why he is liked is because of the purity and world view shown by the Joker.

Related introduction:

The reason why the Joker can be so pure in evil is entirely because he has raised evil to the level of theory. Not only does he have a logically self-consistent worldview, he even realizes that proving the correctness of a theory is not enough to be logically self-consistent, but also requires the support of a large number of social experiments.

The Joker's purpose throughout the movie is very clear from beginning to end, that is, he wants to prove the correctness of his theory and transform Gotham into what he ideally wants.

Extended information

At first, Jerry Robinson wanted to create a super villain image that could rival Batman. This would be an existence that could continue to cause trouble for Batman, a A devilishly evil yet hilarious villain.

Jerry Robinson found inspiration from the playing cards at hand, named the character "The Joker", and designed a playing card with the clown's head as a concept drawing . Bill Finger believed that the image of the character would not be complete just by having the Joker possess abnormal thinking.

He gave the clown a terrifying smile based on the appearance of Conrad Veidt in the 1928 film "The Man Who Laughs", and then wrote the first script for the clown, Bob. Kane and Jerry Robinson finished the painting together, and just like that, the Joker was born.