Batman and Robin

The Joker is the more diabolical and and unpredictable master criminal in Gotham City, possibly the world. He has no sympathy for anyone and seems to believe that men are basically just animals, there is no difference between them and he treats them that way. He causes a lot of problems for Batman and Robin due to his unpredictable nature and absolute careless disposition towards death. The Joker was based off of Conrad Veidt from his performace in The Man Who Laughs. The Jokers real name has never been said in the comics, and his true origins are not known. Some think that he may not be insane, but super-sane, and recreates himself each day to deal with the everyday troubles of life. There is some really great info on the wikipedia page for the Joker. The Batman and The Joker have had many chances to kill each other years, but always end up letting each other go, due to Batman’s unwillingness to be a murder, and the Joker’s amusement and obsession with Batman.

Some good quotes from the Joker-
“Chuckles: I’m betting the Joker told you to kill me soon as we loaded the cash.
The Joker: No, no, no, no, I kill the bus driver.
Chuckles: Bus driver? What bus driver?
[a school bus drives through the wall and kills him] :

“Starting tonight… people will die. I’m a man of my word. HAHAHAHA”

“The only sensible way to live in this world is without rules!”

“See, I’m not a monster…I’m just ahead of the curve.”

And lots more great quotes can be found here at imdb.