The Joker is the main antagonist of The Dark Knight. He depicted in The Dark Knight is often considered the darkest version of the Clown Prince of Crime since his early beginnings in DC comics (prior to a softening of character) perhaps somewhat due to the popularity of Dark Knight some of this Joker's extreme sociopathy has began to sink into the mainstream Joker but in general they are still considered very different criminals in the way they act and think.
The Dark Knight
Several months later a group of bank robbers under the direction of the Joker, robbed Gotham Bank which was used as a money-laundering front for Gotham's gangs. The clown mask wearing robbers whittled down their own numbers within minutes in a series of calculated betrayals. Finally only "Bozo" remained, who revealed himself as the Joker to the Gotham Bank Manager, who had earlier confronted the robbers with a shotgun. In addition, largely because he couldn't resist appearing on-camera, he also deliberately unmasked himself in front of a surveillance camera and posed. The Joker then escaped with the bank's cash in a yellow school bus, concealing his identity by driving within a convoy of other buses, and also leaving the manager at the mercy of a gas grenade stuck in his mouth. Shortly following the bank robbery, an Italian crime boss mentioned the Joker's recent theft of Mob owned cash to his fellow crime leaders at a business meeting, dismissing him as a threat and saying that he was a "nobody" wearing a "cheap purple suit and make-up." The Joker, overhearing this comment and the plan presented to the Mob by Chinese mobster, Lau, arrived unannounced at the meeting while faking a laugh, as he saw their "so called plan" as a bad joke. The mobsters were at first unwilling to hear him out, and Gambol, one of the crime lords who seemed to take the most dislike for the Joker, sent one of his men to take him out by force. The Joker states that he won't kill Batman because he is simply too much “fun” and Batman won't kill him because of his “moral obligation.” In the movie, instead of trying to kill Batman, the Joker attempts to show Gotham and subsequently Batman that anyone can be as bad as the Joker under the right circumstances. The Joker unexpectedly performed a magic trick by making a pencil "disappear," and embedded the pencil in the table, and shoved Gambol's man head-first into the pencil where it indeed disappeared inside the man's head, instantly killing him. The Joker also mentioned that his suit wasn't cheap and that they ought to know this since they bought it, which meant that he used the money he stole at the start of the film to buy his suit. He proposed that it was Batman's interference that had resulted in idealistic leaders like Harvey Dent rising in popularity, and offered his services to kill him for half of all the money that Lau, an illegitimate Chinese accountant, took away from Gotham for safe keeping. He also warned them that Lau would betray them if arrested, claiming to know a squealer when he saw one. While the Bratva mobster, Chenchen and Maroni were interested, Gambol, angered by the Joker's lack of respect, attempted to attack him, forcing the Joker to reveal his insurance policy: several grenades hidden under his coat, allowing him to make a quick escape. Frustrated, Gambol proceeded to put a bounty on him. The Joker later took revenge that night by having his men come to Gambol, claiming to have killed the Joker. In a bit of unintended tragic irony regarding the fate of his actor, the Joker's 'dead' body is brought inside in a garbage bag before attacking Gambol and proceeding to tell him the origin of his mouth scars as a way of psychological torture and intimidation, then when Gambol is most terrified and shaken, the Joker proceeds to kill him with the knife. Then with the remains of Gambol's men overpowered and at his mercy, he takes a pool stick and breaks it in half, making it spear-like and says that there is only one spot open at the moment to join his "team", then throws the piece of sharp stick at the middle of Gambol's scared men and has his gang, made up mostly of mentally-ill and unstable vicious crooks escaped from Arkham Asylum who seem to have taken the Joker as their leader, to make Gambol's men fight to the death with the stick until only one is left, and advising them to "make it fast". Eventually, realizing that Batman had retrieved Lau from Hong Kong and that the police had struck a deal to testify against them, Sal Maroni and the Chechen relented, finally hiring the Joker to kill the Batman. The Joker first kidnapped a Batman impersonator, filmed his murder and hung the body, complete with white make-up and a Joker scars, outside the mayor's office. In the murder tape he sent to the media, the Joker viciously mocks Brian Douglas (Batman impersonator) as well as terrorize him to the point of leaving him absolutely frozen and weeping, as well as taunting his beliefs and his actions. Then when he has finished humiliating and terrifying him, the Joker proceeds to give Gotham an ultimatum. Batman must take off his mask and turn himself to the authorities and every day the Batman refuses to do so, he will murder innocent people day after day. As a result of the Batman not turning himself in, the first major victims were Janet Surrillo, the judge presiding over Dent's indictments, and then Commissioner Loeb the former via car-bomb and the latter via inserting acid into the Commissioner's scotch, respectively. Later, the Joker and his gang stormed a fundraiser at Bruce Wanye's penthouse to kill Harvey Dent. When he was unable to get the guests to inform him of Dent's location, he decided to settle for killing off the guests. He then attempted to threaten an unintimidated guest (whom he noted bore a resemblance to his own hated father), before eventually attempting to kill Rachel Dawes. Dawes attempts to drive him away, with a knee to the crotch, but he laughs it off and becomes more interested in killing her for her having "some fight in her." He was then confronted by Batman. The Joker only managed to escape by throwing Rachel Dawes out a window, who Batman then lept after and saved. This encounter also led him to initially suspect that Batman's true identity was Harvey Dent. The killings then continued with two innocents and an attempt on the mayor's life at a memorial for the murdered police commissioner. The Joker appeared in public without makeup, impersonating one of the guards, as well as having most of his gang impersonate the rest of the Honor Guards. In order to further ensure that the GCPD is kept on its toes, he also placed a sniper rifle on the windowsill of the apartment room, as well as a timer to release the blinds for the GCPD sharpshooters to shoot at anyone hapless enough to be caught in the trap. Afterwards, Joker, still disguised as an Honor Guard, shot his rifle at the mayor, Gordon was struck in the back after willfully leaping in front of Garcia, in order to fake his death to avoid any future attempt by the Joker of attacking him with his family at home. As a result of this, Batman told Dent to call a press conference so he could reveal his identity and stop the killings. In a surprise move, Dent instead claimed to be the Batman himself and was subsequently arrested. While being transported the Joker and his gang attacked the caravan of police vehicles to kill Dent with his weapons. Batman soon arrived to stop the assault, but stayed his hand at killing the Joker. The Joker prepared to unmask Batman but Lt. Gordon, newly resurrected from his hoaxed death, stepped behind him and aimed his shotgun at his back, saying "We got you, you son of a bitch." The Joker was successfully jailed at MCU, and as a direct result, Lt. James Gordon was promoted to Commissioner by the Mayor. He also does a sarcastic clap for the newly-promoted Commissioner. Dent and Rachel each awoke tied to chairs with barrels of explosive material surrounding them and a speakerphone hooked up to the other's location. Rachel confessed her love for him and agreed to marry him. Dent fell on the floor and his left side was completely immersed in turpentine. Batman arrived but found the D.A. instead of Rachel. He realized that the Joker had lied about Rachel and Dent's whereabouts to further crush Batman's morale. Batman rescued Dent as the building exploded and the District Attorney's face was badly burned, while Gordon was unable to rescue Rachel before the explosion. In the hospital, Dent was driven to madness over the loss of Rachel, and blamed Batman, Gordon and the Joker. This act caused Sal Maroni to tell Gordon the Joker's location, finding him and his craziness "too much" for business. The Joker later met the Chechen in a container ship with Lau and was given his reward: half the mobs smuggled money, which he casually burned along with Lau. He then betrayed the Chechen and took control of his men. He declares that Gotham deserves a new breed of criminal - one unmotivated by money or power but who commits crime purely for fun. This corresponds with something Alfred said to Bruce Wayne earlier in the film - "Some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn" The Joker then made a call to a news program where Reese was threatening to go public on the news with information about Batman's identity. He was interrupted by the Joker who stated he had changed his mind, believing Gotham to be too boring without Batman. To "give others the fun" he threatened that if someone didn't kill the employee in sixty minutes he would blow up a hospital. Gordon then abandoned his ambush on the Joker to focus on evacuating all city hospitals. During the mass evacuation, the Joker disguised himself as a nurse (still wearing his trademark face paint) and entered the hospital room of Harvey Dent. He first apologized to Dent, maintaining that he was not responsible for Rachel’s death as he lacks any idea for the repercussions of his actions, while the restrained Dent attempts in vain to kill him. The Joker introduces the former D.A. to his view of the world that his time in Gotham has introduced him to, that people, or "schemers" as he calls them, are the truest form of evil in the world, as it is them who lay out the plans of society, including when human lives are expendable. To prove his argument, he points out that if his threats were aimed at 'gangbangers' or 'soldiers', then people wouldn't really care as society trains them to see the death of such people as acceptable. Thus, he turns the disillusioned Dent against society and against the "schemers" who put his and Rachel’s life in danger, namely the corrupt cops who kidnapped them, as well as the "schemers" who viewed Rachel's life to be expendable, namely Batman and Gordon. Giving Dent a gun, the Joker advised him to break away from the law that failed him and turn to chaos, which the Joker describes as the only truly fair system, as the fate of everyone would be only decided by chance, without the interference of the flawed laws of Man. Dent responded by flipping a coin to decide the Joker's fate, giving him the same chance Rachel had. Soon after Dent left, Joker detonated the hospital, skipping merrily away (pausing and hitting his detonator when most of the bombs temporarily fail to blow). He and his men then steal one of the nearby evacuation buses and kidnapped the TV reporter and his crew inside. The Joker declared that he would rule the streets and that anyone left in Gotham would be subjected to his rule. He told people they could leave now but that he would have a surprise for them in the tunnel and on the bridge, which people then avoided, using instead two ferries, one ship full of ordinary civilians and one of criminals, as Gordon feared the Joker would want to recruit them. However, the Joker had loaded each of them with explosives. In hopes of showing everyone how evil and corrupt they can be, he gave the passengers of each ship the detonator to the bombs to the other and offers both survival if they detonate the other ferry. If they didn't choose by midnight, the Joker would blow up both ships. Batman discovered not only the Joker's location at an unfinished skyscraper, but that the majority of his "gang" were actually hostages wearing clown-masks with unloaded guns taped to their hands and that the people dressed as hostages were the actual criminals. Batman was forced to fight not only the Joker's men but the SWAT teams as well to save the hostages. He finally confronts the Joker, which led to a final battle between the Joker and Batman (with the Joker using a metal bar and a knife). But Joker manages to get the upper-hand and pins Batman under the scaffolding. He gleefully waited as the ferry's deadline neared, and was visibly disappointed when both groups of passengers refused to kill the other to save themselves. The civilians voted to blow up the other ferry, but could not bring themselves to actually do so, while one of the men stepped forward and, taking the detonator, threw it out a window, saying that the cops should have done that from the start. As the deadline passed, Batman asked the Joker if he was trying to prove that everyone was as ugly as him deep down, bluntly informing the Joker that he was alone in his corruption and insanity. Before he could detonate both ferries, Batman hit him with his shooting wrist-blades and threw the man over the edge. The Joker starts to laugh as he falls to die, but Batman, refusing to kill him, instead caught him with his grapple gun and leaving him hanging for the police to capture, much to the Joker's anger. With this act, the Joker acknowledged that Batman really is incorruptible but that Dent is no longer the "White Knight"; he's unleashed the scarred man on the city. Joker states that Dent was his "ace in the hole" in his plan to show the people of Gotham that everyone is corruptible, thus undoing Dent's work before his transformation into Two-Face. Batman then angrily left the Joker to dangle helplessly as he started laughing manically and then was approached by the SWAT team who had him at gunpoint. FateHeath Ledger died under mysterious circumstances of a drug overdose before the movie was released. Out of respect for him, the filmmakers did not even mention the Joker whatsoever in the following film, The Dark Knight Rises. Thus, it is unknown what happened to the Joker after he was arrested. But according to the original script of the third movie, it is likely stated that he was imprisoned far away from Gotham City (Possibly Guantanamo Bay) , never to be heard from again. Another likely scenario is that he died by the time of Bane's revolution. The novelization of 'Rises' places him as possibly the one and only prisoner of Arkham, (the way Rudolf Hess was in Spandau Prison) or perhaps he escaped. Nobody was really sure.
The Joker was nothing more or less than a personification of madness, delusional evil, mayhem, cynicism and anarchism. He views himself as not bad, good or neutral but rather a level higher than everyone else when it comes to life. He believes that superficial and meaningless chaos and selfishness is the basic human nature and tries to get everyone to agree with this theory. The Joker was very egocentric in this area as he disliked people resisting or fighting his opinion. The Joker took pride in having reached this conclusion before everyone else and viewed morally strong people as naive, immature and foolish. The Joker was also not greedy and had no interest in money or even companionship. The Joker was really hard to place, as he knew what he was doing was evil by modern standards but at the same time hoped that his behaviour would become acceptable once everyone realized anarchy was the only way to live. The Joker was also abnormally treacherous, uncaring, hypocritical and above all, sadistic. He took immense joy in others being physically or psychologically wounded and even made dead-pan jokes on the occasions. The Joker is also utterly fearless and masochistic which robs Batman of his pain inflicting and fear inducing tactics on his enemies. These traits also make him a good hand to hand opponent for the Caped Crusader, despite him seemingly having no martial arts training, as he frantically charged at Batman and ruthlessly wailed on him, something an opponent with a fear of getting hurt would never have done. Similar to Two-Face, the Joker would leave prominent examples of chaos to chance, such blowing up a hospital or the two fairies. Unlike Two-Face, however, the Joker never left it up to something he could not control, like a coin, instead he let the people of Gotham choose the outcome. He also left no option in which everyone was safe, making it perfectly plain that people were going to die regardless of what option was chosen. The Joker also shared characteristics with the other primary antagonists of the Batman trilogy. Like Ra's Al Ghul and Bane, the Joker did not like the way Gotham existed or functioned, thought that his evil means were justified by their ends, used fear as torture, hid nothing of his plans from the protagonists to induce panic and pigheadedly thought himself "ahead of the crowd," to avoid facing his flaws. He differs from the other two by wanting to revolutionize Gotham city rather than destroy it. He was the only one of the three who was not a martial artist or a member of the League of Shadows. The Joker was also far more maniacal and smarter than they were and was also the only one to never find out Batman's identity. The Joker stood more or less in between the three villains as he was an anarchist, while Ra's Al Ghul was flat out delusional and Bane was admittedly "Necessary Evil," In addition, the Joker, like other insane and purely evil villains like John Doe, Henry Evans and Lord Voldemort, was exceedingly cunning, manipulative through the use of fear, oblivious to his insanity and depravity and flawlessly thorough in his plans. The Joker's only real setback was his blind ambition that everyone is as cruel deep down as he is on the surface which caused his final plan to backfire on him.
Mark Hamill, no stranger to Joker, has called Ledger's performance absolutely terrifying and creepy.Heath Ledger (posthumously) won the Academy Award for Best Supporting Actor for his role as the Joker, making the Joker the only comic book character to ever win an Academy Award.