Jack Napier was a highly intelligent young man who was born and raised in the country before moving (via hitchhiking) to Gotham City in hopes of becoming a stand-up comedian. Due to having a poor sense of humour and/or Gotham not being accepting of his form of comedy due to it being a cesspool for crime, Jack bombed and was forced to take up crime to pay the bills. Jack's robberies were supposedly non-violent (at-least according to him) but one of them ended (by unknown circumstances) with him falling into acid which bleached his skin white, dyed his hair green, left him with one green eye and the other purple, along with a chemical-inbalance in his brain which lead to insanity and becoming the Joker. Deemed a "super-criminal", the Joker was eventually sent away to a new institution called Arkham Asylum which was originally a historic Gotham Colonial Fortress called "Old Fort Arkham" which was transformed into an institute for super-villains although they often broke out to reek havoc on Gotham and come into conflict with the Batman who Joker in particular was obsessed with. Little-to-none of Gotham's super-villains liked one another. While in Arkham, Joker started falling for and in-return seducing his secretary Dr. Harleen Quinzell who saw the good within Jack and took up the super-criminal alias of "Harley Quinn" to become his partner-in-crime as it made her feel free to be with him.
As the years passed, Joker became more and more sickly obsessed with defeating and becoming closer to Batman which ate away at his relationship with Harley. This climaxed one night when, in an attempt to find out Batman's identity, Joker kidnapped and tortured Batman's first Robin, Jason Todd. Harley was horrified and ratted out Joker to Batman and willingly handed herself over for treatment at Arkham with Batman persuading the courts into being lenient on her penalization. As for Joker, he managed to torture Jason Todd into confessing Batman was Bruce Wayne but also Jason completely hated Batman for not having been able to save him. Joker let Jason go free in hopes of returning Batman to bring shame about his failure but Jason Todd simply disappeared and was presumed dead, with Joker eventually forgetting about Batman's secret-identity and Jason Todd's fate due to his clinical-insanity. Joker's mind also repressed Harleen having left him and he replaced her with a woman named Marian Drews, an emotionally-unstable and self-harming bank-teller who he used as a hostage during a bank robbery after she was dumped by her boyfriend and at some point in the robbery Joker simply started referring to her as Harley. Marian played along and developed Stockholm's Syndrome for Joker who tended to her self-inflicted wounds upon returning to his lair and she fell in love for Joker for his evil flaws, while Harleen fell in love with him despite them. Joker however had no memory of Marian not being Harleen.
Years if not decades later, Joker went on a crime-spree which exploited Batman's ever-worsening emotional-instability which was a result of his guardian Alfred Pennyworth being on his death-bed. Batman caused serious property damage in his Batmobile, ran over civilians, and brutally attacked Joker after Joker willingly surrendered at the Axis Chemicals Disposal Plant. In order to prove a point that the two of them weren't so different, Joker pulled out a container of neurotic pills from a nearby broken crate and claimed that even he could go sane (not knowing the pills were designed and planted by Dr. Harleen Quinzell who was still in love with Jack). Batman responded by brutally force-feeding the pills to Joker resulting in him suffering from an over-dose and nearly choking to death while the whole thing was secretly being filmed by Harleen and posted on the internet, causing scandal for Batman and the GCPD due to accusations of police-brutality.
For months Jack used the drugs and locked himself away in Arkham, plotting to get sane and defeat Batman as a sane man but being forced to let go of his borderline-romantic obsession with Batman in the process, although still wishing to prove him wrong and defeat him. After receiving extensive cosmetic-surgery, Joker emerged from Arkham Jack Napier again and filed a lawsuit against the GCPD for police-brutality as-well as accusing Gotham's government and corporate 1% of using crime and Batman as a means to profit off of the unknowing tax-payers by using super-criminals as fear-propaganda to pay taxes while investing little-to-no money in actually trying to cure the patients of Arkham and instead letting a free-from-payroll vigilante do the GCPD's job for them. After this, Jack returned to his lair and met with Marian who he apologized to for the years of emotional and physical abuse he inflicted on her then proposed to her, promising that he'd treat her the way she deserved to be treated. Marian violently rejected Jack's offer but was fended off by the original Harley Quinn who fought her with the help of her pet hyenas Bud and Lou then took Jack away and explained to him that when he was Joker that she left. The two proceeded to fix things between the two of them and start dating again.
Jack now planned on repaying the debts which he owed to Gotham City from his years as the Joker so he decided to become Gotham's "White Knight" and help Gotham in a way that Batman couldn't, as a politician. At first, Joker was simply an advocate who used blood-money to build a library in the low-income neighbourhood of Backport which was the primary spot of Gotham Crime and Batman attacks, this caused Gotham's 1% to take advantage on the constantly damaged buildings to replace them with their own which they bought for cheap and sold/rented for a lot without Batman (or Bruce Wayne) being any the wiser of the damage he was doing. To exploit the affair, Jack came into contact with his old super-criminal associate Dr. Jervis Tetch AKA the Mad Hatter and had him use his mind-control technology on their fellow super-criminal, the shapeshifer Basil "Clayface" Karlo. With Clayface hypnotized, the took extracts from his body and poured it into drinks which they later fed to super villains including the likes of Oswald "The Penguin" Cobblepott, Edward "The Riddler" Nygma, Dr. Pamela "Poison Ivy" Isley, Harvey "Two-Face" Dent, Dr. Jonathan "The Scarecrow" Crane, Waylon "Killer Croc" Jones, Arnold "The Ventriloquist" Wesker, Roxanne "Roxy Rocket" Sutton and Mary "Baby Doll" Dahl at a truce meeting. The drugged drinks allowed Jack to mind-control Clayface and use him as a hive-mind to control the other super-criminals and their gangs so that they would cause a massive riot in Backport, destroy Jack's library so he looks innocent, and allow Jack to access Backport's public records department to steal the files which proved that the 1% amorally benefited off of Batman's recklessness in the neighbourhood before bringing it to the public.
After gaining this information however, Joker's army was stolen by Marian (now calling herself Neo-Joker) who refused to believe that Jack had gone sane and wished to bring him back. She sided with Mad Hatter, kidnapped Clayface, and took the hypnotized army for her own. Using stolen-information, Jack began campaigning to become Gotham City's newest councilman and lead a peaceful protest-march in Backport only to be stopped by the GCPD he wished to reform as he "didn't have any permits". Jack handed himself over to the police peacefully but was brutally attacked by Batman in-front of his supporters, further cementing Batman's image as a reckless and violent force in Gotham.
- Genius Level Intellect: After taking an IQ test, Leslie Thompkins confirmed that Napier scored "well beyond the level of genius".
- Hand-to-Hand Combat (Basic)
- Indomitable Will
- Political Science
- Unknown Drug: Napier uses the drug that restored his sanity as an anti-psychotic.
- Enhanced Strength: The drug is also a steroid.
- Enhanced Strength: The drug is also a steroid.
- This version of the Joker is the third one to have "Jack Napier" as his true name. The first version of the Joker who bore such name as his real identity was the Joker portrayed by Jack Nicholson in Tim Burton's 1989 Batman film, exclusive to the continuity of the Burtonverse film series and who was created by Sam Hamm and Warren Skaaren. and the second was the Joker from the DCAU although the name was only ever shown on paperwork in the episode Joker's Wild and mentioned in Dreams in Darkness
- The name "Jack Napier" is a pun on the word "jackanapes", meaning an an impudent or mischievous person.
- As the Joker Napier has heterochromia iridium; his eyes are different colours (his left eye is green and his right eye is purple) but when he's Jack Napier both of his eyes are brown.
- 8 Appearances of Jack Napier (White Knight)
- 9 Images featuring Jack Napier (White Knight)
- 5 Quotations by or about Jack Napier (White Knight)
- Character Gallery: Jack Napier (White Knight)