The Joker was a super villain and Batman's archenemy. With an unknown past, sadism, pronounced sense of unpredictability, the Joker suddenly became Gotham City's most notorious criminal, bent on tormenting Batman and Robin and killing as many people as he could out of pure glee.
The Joker was originally an unidentified criminal operating under a number of aliases, who started out as both a hitman and a chauffeur working for the Valestra mob. One of his last known jobs took place in Europe on the Mediterranean Coast. His target was businessman Carl Beaumont after mob bosses Sal Valestra, Buzz Bronski and Chuckie Sol discovered he had embezzled from them. Beaumont’s daughter, Andrea, returned home from grocery shopping, only to see the thug emerging from the house, casually walking past her. Horrified, she rushed inside to find her father murdered in cold blood.
Returning to Gotham City, the thug formed his own gang and staged a robbery at the Ace Chemical Plant, which was thwarted by Batman. Either because Batman threw him, or he stumbled after getting punched, the thug fell off a catwalk and into a drainage vat of chemical waste that washed him out into the river, changing his life forever. The chemicals had an adverse effect on him: they dyed his hair green, his skin was bleached white, his lips were permanently stained red, and he was driven completely, irrevocably insane. Vowing to show the world the triumph of his "comic genius", thus began the career of one of history's most dangerous and intelligent psychopaths: the Joker.
A frequent inmate of Arkham Asylum, the Joker was often psycho-analyzed at one point by Dr. Harleen Quinzel. The manipulative Joker quickly won Quinzel’s trust, painting himself as a misunderstood soul crying out for the world to accept him. He once claimed that he was routinely abused by his alcoholic father, and that the only time he had seen his old man laugh was at a visit to the circus. Over time, Quinzel later found herself madly in love with the Joker, and eventually took it upon herself to break him out of Arkham and become his new henchwoman, Harley Quinn. Though claiming to reciprocate her affections, the egotistical Joker saw Harley as merely useful, and would frequently inflict verbal and physical abuse on her if she upstaged him or simply got on his nerves. Many a time he would literally throw Quinn out onto the streets until he inevitably decided he wanted her again, and she would inevitably come crawling back .
The Joker's plans had little prejudice. Although he showed particular delight in playing his jokes on the most ordinary, innocent victims, like mild-mannered salaryman Charlie Collins, he was just as dangerous to Gotham City's highest level officials such as Commissioner James Gordon, or Mayor Hamilton Hill. But Joker has had his share of provocations. He was one of three villains to travel to Yucca Springs on an invite from Hugo Strange claiming to know the identity of Batman. Ex-businessman Cameron Kaiser deliberately made his casino resemble Joker's look to draw the villain out as a means to trick Joker into wrecking the casino so he'd get away with the insurance, although this plan ultimately backfired when Joker, thanks to information revealed by Batman on the plot, decided to instead kill Kaiser and then manage the casino from behind the scenes.
Depending on the joke, the Joker's plans could range from small-scale to global. On one occasion, he tried to con his way to a local comedy trophy (or more accurately, the title of "funniest man alive"), that he was denied in disguise on account that he registered late, by using the Mad Hatter's mind control chips on the event's judges. Another time, the mad clown stole a nuclear warhead and almost successfully set it off on Mayor Hamilton Hill’s residence. One of his most infamous schemes involved infecting all the fish in Gotham Harbor with his Joker venom, then demanding a copyright for the disfigured creatures which now bore his grinning visage. When refused this, he went on a killing spree, infecting several bureaucrats of the Gotham Copyright Office with his Joker venom. He also once broke out of Arkham via Christmas Tree rocket to cause chaos on the streets in Gotham via an AWOL tank with a Santa on it, a giant cannon firing at various parts of Gotham, and a bomb being planted on a rail bridge that was timed to explode just as the train was to make its 11:30 arrival as part of a "Christmas special", all in an attempt to lure Batman over to give him his "Christmas Present": a pie in the face.
Some time later, the Joker took up residence in the rotting remains of the World of the Future Fair, seemingly alone. When the mysterious Phantasm began hunting down former members of the Valestra Mob, the now-aged and scared Valestra foolishly tried to buy the Joker’s help, believing the Phantasm to be Batman gone mad. The Joker, however, disposed of his “pal” Sal, and discovered the true nature of the assassin. He later approached councilman Arthur Reeves with the intent of blackmailing him, but injected him with Joker Toxin instead. He correctly deduced that his former gang’s executioner was none other than the daughter of the man he had murdered years ago, and was ready when the Phantasm came for his head. The two engaged in a brutal fight, but when Batman intervened the battle became a one-on-one with the Dark Knight. After the battle, the beaten Joker found himself at the Phantasm’s mercy, and as the amusement park was burning to the ground, the Joker couldn't help but laugh, which eventually made Phantasm let him go after seeing that he simply was not sane anymore.
Batman shut down the Joker's operations in Gotham City on a routine basis but Joker really did go bankrupt on a few occasions. One such instance caused him to travel to Metropolis, where he briefly allied himself with Lex Luthor to kill Superman for one billion dollars. Luthor scoffed at Joker, claiming he was overconfident in his ability to kill a superpowered Kryptonian when he had been unable to kill "a mere mortal in a Halloween costume", but agreed to pay should he succeed. Joker planned to use the statuette Laughing Dragon actually made of Kryptonite. Joker's plans fell apart when Batman deduced what the antique was made of and headed to Metropolis, reluctantly cooperating with Superman to defeat the villain. Fearing Joker's failures were exposing him, Luthor called the deal off. Consolidating his losses, the Ace of Knaves kidnapped Lex and hijacked the experimental Lexwing assault vehicle, planning to destroy everything Luthor had built for fun (as Luthor had a hand in building half of Metropolis). The plan backfired when, in an engagement with Batman, Joker's exploding marbles fell across the plane. While Batman and Superman rescued Luthor and Harley Quinn, Joker was helpless on the crashing plane, laughing manically as it exploded over the river, supposedly killing him.
The Joker returned to Gotham City a month later, still bankrupt. He unwittingly received a $250 million inheritance from his former gangland rival Edward "King" Barlowe. Joker immediately spent the first million on various pursuits, such as hiring a defense team to wipe his criminal record clean and even trying to buy Nightwing and Batgirl off. However, Joker was duped. The majority of the money was counterfeit and the IRS was claiming its dues, which Joker could not dispute without an embarrassing admission that he'd been tricked, thus making him a laughing stock in the Gotham underworld. Desperate, Joker tried to steal a routine money dispersal from the Gotham Mint without using any of his trademarks until Batman intervened again. Trying to jump over the ship, Joker was stopped from doing so by Batgirl as it would be pointless to go after the money that went over board. However, crying, Joker said "I don't want to save it. I want to go with it.", implying he was sad enough to commit suicide. Joker was then returned to Arkham with a little payback from Harley on the way.
During the seven-year anniversary of his transformation into the Joker, the Gotham Insider made a live report from Ace Chemical Plant. The Clown Prince of Crime made an appearance and attacked the news crew. Jack Ryder was doused with Joker venom then shoved into a drainage vat. Ryder transformed as well, but the combination of the chemicals and the laughing gas pushed Ryder further, giving him an energetically maniac yet still basically conscientious personality. Fashioning himself into the crazed vigilante known as the Creeper, he went on a rampage to get revenge on Joker. As a result, Joker found himself in the bizarrely terrifying situation of being relentlessly pursued by this new insane superhero of his own inadvertent creation. Although Creeper's mania is benign, his methods are so extremely wild and frantic that the Joker practically begged Batman to arrest him, clutching Batman's cape and crying "He's a lunatic!". Batman then cuffs Joker while somewhere along the line, Joker was saved and Batman sedated Creeper.
In another routine shut-out, the Joker was forced to move his enterprises outside of Gotham City. This time he chose the Midwestern town of Dakota. Joker planned on forming a metahuman gang. However, Batman, Robin and Static teamed up and escaped Joker's death trap, arresting the Clown Prince of Crime in the process.
Some time later, the Joker wound up in Metropolis again. He was just in time to meet Lex Luthor's Injustice Gang. Lex, remembering the fate of his past alliance with the Joker years earlier, simply ordered him to leave. Undeterred, the Joker knocked out Solomon Grundy with a gag airhorn when he attempted to remove the Clown Prince, and proceeded to tell Lex that his expertise on Batman made him invaluable to the Gang. After the Joker demonstrated his point by revealing the tracking device Batman had planted on Luthor, Lex decided to keep him around. The Joker's only condition was that he got to do whatever he wanted with Batman after the Justice League was successfully destroyed. Using the tracker Joker had found, the Injustice Gang captured Batman and imprisoned the Dark Knight. Joker started to try and convince Luthor to kill Batman whilst they had the chance, but Luthor refused. Joker is later seen with Ultra-Humanite and Lex as they try to deactivate the defensive system on Batman's utility belt which they do so successfully and find a communicator and key to the Justice League's space station. Luthor then sent the other Injustice Gang members to the space station, which was being guarded only by the Martian Manhunter, to plant a bomb on the headquarters and call them back. However, the Justice League survived and eventually defeated the Injustice Gang. Deciding to cut his losses, Joker pulled out a handgun and attempted to kill Batman, only to learn that his nemesis had not only freed himself in the confusion, but manipulated events in his favor throughout the entire scheme. Batman easily knocked out Joker to end the conflict.
Continuing to cause more chaos, the Joker discovered and entered the secret compound Section 12. Since the compound was under the supervision of a secret initiative, he took some of their technology for later uses. Joker then freed the compound's captives and fashioned them as a card deck hand metahuman gang. Next, he purchased air time on several networks under the moniker "Gwynplaine Entertainment" and broadcast a live feed of Las Vegas. Joker secretly planted several dozen high explosives all throughout the city. Though the Justice League managed to disarm the bombs, the bomb stunt was merely to attract viewers throughout the world. The real plan was to use the powers of his gang's fifth member Ace. Joker transmitted Ace's thought waves across the air to render everyone under a mass psychosis. When Batman confronted Joker alone, the Dark Knight managed to reveal to Ace that Joker had held onto a special headband used to nullify Ace's powers. Ace, in turn, used her power on Joker and temporarily rendered him catatonic.
The Killing Joke
The Joker eventually recovered from his catatonic state. As he was deciding that the "game" between him and Batman was growing old, the Joker devised one last scheme directed at Batman's "family". After Dick Grayson left for Bludhaven, Joker and Harley Quinn lured and kidnapped Tim Drake, Dick's successor as Robin while the Boy Wonder was alone on patrol, unaware that this is a trap. In the former partially demolished Arkham Asylum, Joker systematically tortured Robin for three weeks. After several serum injections and electric shocks, Robin revealed all his secrets to the Clown Prince of Crime, including the fact that Batman was really Bruce Wayne. Joker then completed the "makeover" by splicing their DNA together, resulting in his victim's face contorting into a Joker like smile and then dressed as a crude version of himself named "Joker Junior" (or "J.J." for short), much to the horror of Batman and Batgirl. Joker even went far enough to document the torture to show in the operating theater to Batman as the "Our Family Memories" video all so that he could crush Batman's spirit. Vowing to break the Joker, the enraged Dark Knight had his final battle with the Clown Prince of Crime. While succeeding in enraging Batman, Joker delivered a knife to Batman's knee, crippling his nemesis. However, not even Joker could fully turn J.J., and rather than shoot Batman and "deliver the punchline", J.J. shot and killed Joker instead. Joker's last words were "That's not funny... That's not..." before gasping his last breath and collapsing from the mortal wound, dead. Then Tim suffered a mental breakdown while Batgirl tried to comfort him.
Though buried deep beneath Arkham Asylum's remains, the villain's last bid tainted the trio and caused the retirements of Robin and Batgirl leading to the estrangement of all members of the Batman family. Tim Drake would also suffer lasting trauma into adulthood despite having been helped to sanity a year following Joker's death by Leslie Thompkins.
Despite his death, the Joker's criminal mastermind and homicidal legacy would live on for years. Whilst the people of Gotham City were free of the villain, several teenager street gangs were formed to honor the Clown Prince of Crime's destructive legacy, most notably J-Man and Terminal, although these, unlike the Joker, were mostly minor petty criminals and rarely killed people.
Unknown to anyone, the Joker's greatest experiment on Tim Drake involved the usage of stolen cutting-edge genetics technology to encode his own DNA into a microchip that was implanted at the top of his victim's spinal cord. Forty years later, Joker's subconscious reawakened and began to assume control of Tim's body and plot a return. If Drake's family ever got worried, he'd simply call Tim's wife in his host's voice saying he'd be working late.
Using Drake's knowledge of communications, Joker staged a series of corporate thefts utilizing a sub-group of Jokerz. He then had his Jokerz raid Bruce Wayne's "Welcome Back" party, both to steal the final necessary piece of equipment (a systems scanner), and to expose to all of Gotham City (including Wayne) that he's "back in town". He later dispatched his Jokerz to kill Terry McGinnis (though it's never explained how The Joker knew about Terry McGinnis being Batman) while Joker himself personally broke into Wayne Manor and dosed Wayne with Joker venom. He also kicked Bruce's dog Ace, as well as making sure that Drake's old Robin outfit was shredded apart while vandalizing the place in the process, nearly killing Wayne had Terry not supplied Wayne with an antidote that Wayne had earlier hidden.
With the stolen communications technology, Joker created a satellite jammer and hijacked control of a Hyperion class defense satellite orbiting the planet so he could impose his will on Gotham. His first target was the yacht belonging to his ally Jordan Pryce after dispatching his Jokerz to "tie up a loose end" by trapping him aboard. After Terry deduced that Drake was likely involved in Joker's scheme, Joker had anticipating that Terry had deduced the connection and set up a trap involving a hologram of Drake, as well as a recording that activated after Terry touched the holographic representation of his victim that "confirmed" that Drake had indeed joined with Joker, as well as unveil that he planned to use the hijacked satellite to cause untold acts of destruction on Gotham. Eventually, he used the hijacked satellite to attack Terry, although not before McGinnis uncovered his hideout.
Joker then regressed to the original form of his new body's owner before trapping Terry with an electronic restrainer and then demonstrating his transformation into Joker to both Batmen. Having revealed the mystery of his revival, Joker planned to crush the new Dark Knight's spirit by destroying Wayne Manor with Bruce inside then Terry's family and girlfriend - all while drawing a smiley face upon Gotham City's ashes. But before he could activate the satellite, Ace ambushed Joker and tackled the mad clown, freeing Terry in the process. Joker then used his joy buzzer to fend off a second attack from the Great Dane and moved in to finish him off, but a kick to the jaw knocked his joy buzzer into vital equipment.
After the jamming system accidentally redirected the satellite's laser straight to Joker's hideout, Terry tried to take Joker back to Arkham Asylum before the laser killed them both, but Joker refused and began one last battle with the new Dark Knight, using his host's knowledge of every trick the original Batman and Robin knew. However, the new Batman decided to "fight dirty" and, after kneeing Joker in the crotch as proof that he's absolutely nothing like Bruce Wayne, began to taunt and laugh at him. By insulting his supposed poor attempt at jokes, gags, his sense of humor in general, and even his own creation, Batman knew that his predecessor had never insulted Joker’s ego in such a manner, preferring to fight one-on-one in stoic silence. This act sent Joker into a complete mental breakdown and he began throwing everything he had, including mini-pocket bombs. Within moments of the satellite's beam hitting the building, Terry used Joker's own lethal joy buzzer against him; electrocuting him, and incinerating the microchip encoding his DNA on Drake’s body. With the microchip burnt to ashes, Tim was restored and Joker's threat was ended once and for all.
The Joker was demonstrated to be a psychopath, even prior to his chemical bath. He harbored little remorse regarding any murders he committed under Sal Valestra's gang, and also intended to start his own criminal gang. In addition, one of the few photographs of Joker pre-chemical bath that existed (which had Batman deduce who had killed Andrea Beaumont's father) had him holding a cigarette, implying that, at least pre-transformation, he had been a cigarette smoker.
After being dunked into a chemical bath, his insanity increased, making him among the most dangerous criminals in Gotham, attempting to commit mass murder all for the sake of jokes. He has little regard for his own life and safety, even laughing in instances where his own death was seemingly inevitable, as evidenced by his reaction when the fairgrounds were exploding around him alongside the Phantasm's preparations to kill him, as well as his reaction when he saw, during a failed evacuation from the doomed LexWing, his explosive marbles rolling towards him.
Once, he even deliberately aimed a gun turret on an airplane he planned to make an escape in on the nuclear bomb he had set to detonate, fully acknowledging that he will most likely die from the bomb being set off just to ensure Batman could not disarm the bomb. His lack of regard for his survival was such that, after Batman came very close to killing Joker in anger for the torture of Tim Drake, Joker referred to the act of Batman killing him as "that kind of fun" when calling Batman out by stating he should have done it years ago. When the returned Joker believed that he finally was about to eliminate Bruce once and for all, he admitted that he despised Bruce and actually "hated his guts," even going as far as to blow a raspberry at him. 
Despite this, however, the Joker nonetheless earlier gave his nemesis a eulogy when it seemed as though the latter had died, although mostly because he felt he allowed crime to have "a punchline". His personality was best summed up by Bruce Wayne when Terry McGinnis asked if he was the top of the rogues gallery, "It was no popularity contest. He was a psychopath, a monster."
Despite his evident insanity, the Joker was also shown to be quite intelligent, which was best demonstrated with the Phantasm murders, where he very quickly deduced the Phantasm's true identity, Andrea Beaumont, just from hearing her name on a secretary's announcement, knowing it couldn't have been her father as he had personally made sure he was dead from his prior life as a mob hitman. Other demonstrations of his intelligence include his deliberately stealing the Laughing Dragon due to not only deducing Superman's fatal weakness to Kryptonite, but also the fact that the infamous heirloom was made out of the material, and when he deliberately chose to forego his usual trademark gimmicks for his crimes, and even sent a body double to the Iceberg Lounge while he went to rob the U.S. Mint of cash specifically to avoid having Batman track him down. Also, he somehow figured out Batman's tactics due to years of dealing with him, evidenced by how he discovered Luthor was being tracked by Batman much to the latter and the Injustice Gang's surprise. when the Injustice Gang managed to capture Batman, he repeatedly insisted that they kill him when they have the chance due to realizing just how much of a threat he posed to their plans.
Even when he was "reborn" via Tim Drake, his intelligence hadn't died down, as evidenced by how he managed to deduce the true identity of the new Batman (how he deduced it however is unknown), as well as anticipating that the new Batman would deduce that Drake was in on his schemes. He also anticipated that Bruce Wayne had "monkey-wired" the new Batman and was monitoring everything they were saying at that point, even implying he was hoping for this in order to expose the truth to his old archnemesis that Drake was literally under Joker's control via a Cadmus chip.
The only thing equal to Joker's insanity was his massive ego. He perceives himself as the greatest comedian in the world and the greatest nemesis of the Batman, and will not hesitate to destroy anyone who claims or demonstrates otherwise. One example of this hubris is when he was booted out of a comedy show and got back at the ones responsible by hypnotizing them into becoming super villains in order to cement himself as the "funniest man in all of Gotham", only to end a laughingstock afterwards.
Another blow to his pride is when he was made to believe that he had inherited a massive fortune from a hated rival of his, only to learn that a majority of it was fake and it was a trick to get the last laugh on the Clown Prince, enraging the Joker beyond words and causing him to shoot the TV the message was being played on. Another time is when Harley Quinn managed to successfully capture Batman so that she and Joker can truly live together, but Joker saw this as an insult to his profession and assaulted Harley, going as far as to push her out of a window to her possible death. Batman then admitted that he tricked Harley into calling the Joker because he knew that his ego would never allow another to kill Batman and even went as far as to suggest that Harley came far closer to succeeding in killing him than Joker ever did, further damaging Joker's pride. This revelation leads up to one of the few times the Joker truly loses his cool.
Bruce Wayne would later reference this character trait of Joker's when advising the new Batman on how to beat Joker by referring to him as being "vain" and "loving to talk." Ultimately, it was this arrogance that led to the Joker's demise twice; the first was believing that Tim Drake, having been transformed into Joker Jr., was firmly under his control, only for the boy to resist and end up fatally shooting the Joker in the chest, with the clown using his last breath to remark his disappointment in the following events. The other time was when Terry McGinnis began insulting the Joker's sense of humor, relationship with the original Batman, and his creation, causing the Joker to become completely insane and attempt to choke the boy with his bare hands, allowing Terry to destroy the chip on his neck and end his threat once and for all. Ironically, the latter instance came about after the new Batman decided, instead of blocking out Joker's taunts and powering on through (Bruce Wayne's original tactic of dealing with him), to beat Joker at his own taunts due to realizing that the new Batman himself also "liked to talk."
Owing to his more clown-like appearance, he generally uses more comedy-based elements in his crimes and plans. As such, he also gets angry whenever someone "explains the joke" to him viewing it as not a joke at all. This resulted in him nearly killing Harley Quinn when she explained how she modified the plan for Joker in an attempt to help him kill Batman (alongside the above mentioned massive ego). Likewise, he also tended to use abandoned or otherwise defunct toy/candy factories or warehouses with some sort of comedy/clown theme as hideouts, like Laffco Toy Factory, the defunct World of the Future Fair fairgrounds, Funnibone Shipping, and the Jolly Jack Candy Factory.
Abilities and equipment
Throughout the years, the Joker used a wide variety of instruments to exact his comedic homicides. He is as brilliant as he is insane (claiming to be even smarter than the Batman himself) and it was only through his assistance the Injustice Gang managed to capture Batman and he has sufficient expertise in chemistry and physics to be able to invent gadgetry and concoct elaborate schemes. His equipment included card-shaped blades, guns (of the trick and real variety), joy buzzers (which electrocuted the victim), a wide variety of laughing gases (which incapacitated the victim with laughter), and his deadly Joker venom. Most famously, Joker had a flower attached to his suit. This flower emitted a wide variety of chemicals, depending on the situation and Joker's mood. Laughing gas and acid were popular variants, but the possibilities were limited only to the Joker's mind. Joker also showed some aptitude in engineering evidenced by how he quickly understood the highly advanced Cadmus microchip he stole and successfully converted Robin into a miniature but exact replica of himself during the latter's captivity under him. Joker is also a master torturer and intimidator, he managed to break Robin mentally and emotionally during his captivity to the point where the latter spilled out his secrets, despite the boy trying to resist at first.
The Joker also seemed to have a strange relationship with death, constantly surviving and coming back from potentially fatal things — falling through a smokestack, the destruction of the Lexwing, eaten by a shark, and even being psychically mind-wiped by Ace, to name a few — that should by all rights have ended his career, although the last aspect may have been due to the complexity of Joker's own mind. Even when he was killed by the brainwashed Tim Drake, Joker still managed to cheat death through Tim himself, surviving long enough to come into conflict with the new Batman but was destroyed once and for all.
Originally, the Joker possessed little more than average physical strength, albeit enough to regularly hold his own against the original Batman. But upon inhabiting Tim Drake's mind, he acquired the training, conditioning, and knowledge of the original Batman and Robin, allowing him to easily outmatch the new Batman in a fist fight and shrug off some of Terry's attacks. However this was also due to Terry's inexperience. While possessing Tim Drake, the Joker was physical strong and agile to use the fighting skills of both Batman and Robin into his own personal style which made him formidable against the new Batman until Terry stopped holding back.
Originally, the Joker was slated to be voiced by legendary actor Tim Curry, who at the time had just finished voicing and portraying Pennywise the Dancing Clown from the original TV film adaptation of Stephen King's It. However, the casting ultimately went to Mark Hamill instead, with him being chosen in large part because of his performance as Ferris Boyle in "Heart of Ice". Contrary to popular belief, Tim Curry's rejection was not because of his voice work proving too scary for what was intended to be a children's television program. It was actually because of his voicing style conflicting with showrunner Paul Dini and the other producers' vision for the character, as Tim Curry voiced the Joker as a more straightforward villain, while the producers of the show envisioned the Joker's characterization in the cartoon as being more chaotic and playfully twisted, as revealed in Batman Animated. Some fans had rumored that Curry recorded some lines for the episode "Joker's Favor", but whether this is true or not remains unknown at the current moment.
As an interesting fact, a skeleton is seen wearing a shred of purple clothing with a similar bow flower in the Batman Beyond episode "Joyride" is believed by many to be that of the original Joker. Considering what Terry McGinnis is told that the Joker's body was buried beneath Arkham Asylum's remains as shown in the deleted scenes of Batman Beyond: Return of the Joker, this could very well be true.
During the earlier episodes of the series, he was on a few occasions given the name Jack Napier, which was the true name of the Joker in the 1989 Batman film. However, as the animated series went on, references to the name were dropped, with it eventually being implied in Beware the Creeper that this had simply been an alias. Similar to the 1989 film version of the Joker, this version also worked as a hitman within the mafia, and was also responsible for Bruce Wayne adopting the identity of Batman (in the 1989 film, Joker's role had been direct via Joker, or rather, Jack Napier proceeding to slay Bruce's parents and almost killed Bruce himself; in the animated series, his role was more indirect, as it was his and the Valestra Gang's threatening the Beaumonts and forcing Andrea to break off her relation with Bruce so she could go into hiding that resulted in Bruce fully adopting the identity of Batman).
It should be noted that a recurring gag in the DCAU, which started in the Batman: The Animated Series episode "The Laughing Fish" and was even brought into the Superman: The Animated Series three-part episode World's Finest, was to have an episode finishing with the Joker being apparently killed each time for different reasons, but he later returned in further episodes without an explanation given (except the instance where he was ultimately killed by Terry McGinnis at the end of Batman Beyond: Return of the Joker, dying for good). According to writer Paul Dini, he or Alan Burnett were the ones who pitched the idea to "kill off" the Joker in certain episodes only to brought back him in later episodes, although no explanation for this decision has yet to be given.
Along with the rest of the cast, the Joker underwent a revamp when Batman: The Animated Series streamlined into The New Batman Adventures. Joker's change was relatively minor; however, he lost his trademark red lips, his hair was so dark is was almost black, his eyes were hollowed with white pupils and black sclera, and he was made to appear physically smaller and thinner. Audio commentary on the DVD release of the Superman: The Animated Series three-parter "World's Finest" and "Holiday Knights", reveals that the producers of the DCAU regret the stylistic change, and admit that removing Joker's red lips was a mistake and that doing so was Glen Murakami's idea.
The character was altered again for Batman Beyond: Return of the Joker; this design, using elements from the original design with the second design's angular style, was later used for the character's appearances in Static Shock and Justice League. Like in the original design, the Joker also is shown to have red lips, yellow sclera and green hair, although they were depicted in an extremely dark manner that the color is only identifiable via highlights. According to the DVD commentary of Batman Beyond: Return of the Joker, the Joker's Batman Beyond era appearance (the red eyes and the slicked back hair) were based on an illustration of Hannibal Lecter from the novel The Silence of the Lambs. The redesigned present-day Joker would later be used when the Joker returned in Justice League, although he was modified to appeal bulkier and with a noticeable lurch in his posture.
- Mark Hamill stated that he based the Joker's vocal style on the Chief Blue Meanie, the main villain in the cult 1968 animated film Yellow Submarine. Hamill also stated that the Joker's distinctive laugh was based on a similar laugh he had used playing Mozart onstage in the play Amadeus in 1983.
- While not as obsessed as Calendar Man, the Joker is fond of unleashing schemes on holidays, notably April Fools' Day, Christmas, and New Year's.
- The name 'Jack Napier' was used in Tim Burton's 1989 Batman film and later utilized in the DCAU as well. Dr. Bartholomew refers to him by this name in "Dreams in Darkness", and the name can be seen in a file about him in "Joker's Wild". Later in "Beware the Creeper", it is mentioned that his true identity is unknown and that he operated under a variety of aliases during his criminal career, implying that the man did indeed use a number of aliases and that 'Jack Napier' was simply used the longest or at least the one used before his accident.
- As an hallucination in the Batman: The Animated Series episode "The Forgotten".
- While impersonating Tim Drake in Batman Beyond: Return of the Joker.
- As an hallucination in the Batman: The Animated Series episode "Dreams in Darkness".
|Members of the Injustice Gang|
|Cheetah • Copperhead • Joker • Lex Luthor • Shade • Solomon Grundy • Star Sapphire • Ultra-Humanite|
|Aresia • Copperhead • Shade • Solomon Grundy • Star Sapphire • Tsukuri|