Dini had several names in mind while naming the character, such as Columbine, and eventually settled on the name "Harley Quinn". Dini chose the name for the character to be in line with other Batman characters's names being puns, and also because he thought "Harley was a fun name for a girl". Harley Quinn then became a recurring character in the DC Animated Universe, appearing in The Animated Series sequel The New Batman Adventures, the direct-to-video film Batman Beyond: Return of the Joker, and in non-Batman animation such as Superman: The Animated Series, Static Shock, and Justice League. In February 1994, she made her first appearance in a video game in The Adventures of Batman and Robin, an action platformer based on Batman: The Animated Series.
Transition to comic books
thumb|"Tango with Evil" by [[Alex Ross, from the cover of Harley's canonical debut Batman: Harley Quinn. Widely described as iconic, the artwork depicts Harley dancing with a tuxedo-clad Joker and was later recreated in the 2016 film Suicide Squad.]]
Because of her popularity, Harley Quinn was adapted into DC's comic books. In September 1993 (cover date), a year following Harley Quinn's first appearance in Batman: The Animated Series, the character made her comic book debut in the 12th issue of The Batman Adventures, a series set in the universe of The Animated Series, and became a regular character. Widely considered the definitive Harley Quinn story, Mad Love added dimensions to the character, with Dini introducing Harley Quinn's motivations as well as establishing her as a tragic and sympathetic figure. The story received wide praise and won the Eisner and Harvey awards for Best Single Issue in the same year and was later adapted into an episode of the same name in The New Batman Adventures in 1999. which put her origin in the middle of the Batman: No Man's Land story line. Dini changed Harley and the Joker's relationship to be darker to match the Joker's character in the comics; in the story, the Joker attempts to kill Harley at the first opportunity. Harley's immunity to toxins and enhanced strength and agility, which were gained from a special formula created by Poison Ivy, were carried over from Batman: The Animated Series, with Dini stating that they would give her a sort of "physical edge" over Batman and other heroes.
While pursuing new assignments at DC Comics' offices in New York City, Karl Kesel was approached by former DC editor Matt Idelson to create a pitch for Harley Quinn's first ongoing series, which Kesel accepted, being a fan of the character after having read Mad Love. Kesel called Dodson and asked him if he was interested on working on the comic, to which Dodson agreed, and the two worked for a month on their proposal for the series, which was to make a comic about "love gone horribly, terribly wrong". The decision renewed interest in the character, but the sales remained lackluster and the series was cancelled in 2003. The series also expanded on Harley Quinn's background and early life; in Gotham City Sirens #7, Dini established the character's hometown being Brooklyn, based on her accent and also introduced her dysfunctional family, with her swindling father being described as the main reason for her pursuing psychology.
The first several issues of Gotham City Sirens were written by Dini and illustrated by Guillem March. Other creatives who worked for the series include writers Tony Bedard and Peter Calloway, and artists David López, Andres Guinaldo, Peter Nguyen, Jeremy Haun, and Ramon Bachs.
As part of the New 52 reboot in September 2011, Harley Quinn was reintroduced by Adam Glass as a prominent member of the supervillain team Task Force X in the relaunched Suicide Squad series. The character was heavily redesigned to fit the tone of the book, and was inspired by Harley's designs in the video games Batman: Arkham Asylum and Batman: Arkham City; Her personality had also been depicted to be more violent and psychopathic than her former iteration.
| image2= The controversial cover artwork for Suicide Squad (vol. 4) #1, which introduced Harley Quinn's revealing look for the relaunched title, Glass said: "Harley's always wanted to belong to something. And if not Joker, then the team – and she's finding herself in all this. She's finding her place in the world, that she's not just a sidekick".
New origin
In the seventh issue of Suicide Squad, Glass revised Harley Quinn's origin story, making it reflect the Joker's origins. In the story, the Joker takes Harleen Quinzel to the chemical plant where he originated and pushes her into a vat of chemicals against her will, which bleaches her skin and drives her insane, resulting in her transformation to Harley Quinn. This origin was received negatively by fans, who felt that its removal of Harley Quinn's choice to become the Joker's accomplice willingly, as depicted in her previous origin stories, took out an essential part of her character. Considered to be the most defining writers to work on the character since Dini and Timm, Palmiotti and Conner reinvented Harley Quinn as an antihero who has left her controlling relationship with the Joker behind.
In contrast to Harley Quinn's depiction in Glass' Suicide Squad, Palmiotti and Conner wrote Harley Quinn with a lighthearted, cartoonish, and humorous tone. Her costume has also been changed with a roller derby-inspired costume designed by Conner, which incorporates Conner's favorite aspects of Harley Quinn's early costume and her costume in Glass' run of Suicide Squad. The rest of the series details Harley Quinn's adventures in Coney Island with her supporting cast. In Harley Quinn #25, Palmiotti and Conner reunited Harley Quinn with the Joker; the story depicts Harley Quinn returning to Gotham City to confront the Joker and end their relationship.
With Harley Quinn's longtime friend Poison Ivy being a recurring character in the series, Palmiotti and Conner built on their relationship and hinted at romantic feelings between the two characters; Poison Ivy is shown kissing Harley Quinn multiple times throughout the series, and a sexual relationship between them was alluded to in issue #25.
Controversies
The cover of the first issue of the New 52 Suicide Squad title drew controversy for its sexual depiction of Harley Quinn.
DC Rebirth
DC's June 2016 relaunch of its entire monthly comics line, DC Rebirth, the character appeared in both the one-shot issue Suicide Squad: Rebirth #1 (October 2016), with a design that included design included pink and blue dyed hair tips and a jacket inspired by Margot Robbie's portrayal of the character in the 2016 film Suicide Squad, a change established in the last issues of her New 52 series.
Harley Quinn returned as a regular character in the relaunched Suicide Squad series, written by Rob Williams. The series was canceled in January 2019.
Harley Quinn's relaunched ongoing series is a direct continuation of the former, with Conner and Palmiotti still writing for the character, and Hardin and Timms illustrating the interior art. After having written 64 issues of Harley Quinn's ongoing series, Conner and Palmiotti's five-year run ended with the 34th issue of the series in December 2017, with writer Frank Tieri and artist Inaki Miranda taking over the title. Tieri's run on the series ended with the series' 42nd issue, followed by a two-issue storyline written by Christopher Sebela and illustrated by Mirka Andolfo. The series ended in August 2020.
Harley Loves Joker
In 2017, Harley Quinn co-creator Paul Dini wrote a backup feature for Harley Quinn's Rebirth monthly series entitled Harley Loves Joker, co-written by Palmiotti and illustrated by Bret Blevins, which ran for 9 issues. The story brought back Harley Quinn's classic characterization and focuses on her past with the Joker. Unlike her characterization in Batman: The Animated Series, Dini and Palmiotti wrote Harley Quinn in the story as less of a "doormat", with Harley Quinn and Joker being on equal footing in their relationship. The story concluded with the two-part limited series of the same name, which also expanded on Harley Quinn's past as a former intern in animal research at S.T.A.R. Labs, where she met her pet hyenas Bud and Lou. In the second part of the story, Dini and Palmiotti explained Harley Quinn's change in costume, establishing the character's modern design as a reflection of her having left her relationship with the Joker.
Infinite Frontier
thumb|right|250px|upright|Concept art for Harley Quinn's [[Infinite Frontier design by Riley Rossmo, which combines his favorite aspects of Harley's classic jester getup and more recent designs. Harley Quinn also has a prominent role in the "Fear State" crossover event.
In January 2022, Phillips confirmed Harley would be resuming her previous career as a psychologist.
Characterization
Powers, abilities, and equipment
Harley Quinn possesses multiple superhuman abilities, having won a gymnastics scholarship at Gotham City's Gotham State University.
Harley Quinn is skilled in using various weapons, often employing weaponized clown-themed gag items, including pop guns, rubber chickens, and a gun that shoots a boxing glove, as well as oversized pistols and mallets, the latter being her signature weapon. Other weapons she uses include: unconventional weapons, such as a baseball bat; explosive weapons such as bazookas, customized bombs, and dynamites; firearms, such as pistols, assault rifles, and machine guns; She also has an indomitable pathological will.
Just like Poison Ivy, sometimes and not as much, Harley uses her feminine charm to attract men but only to manipulate them. Unlike the Joker, she is able to simulate sanity, thus being able to pretend to be a "normal" person. In this way, she disguised herself as a security guard, a lawyer and even Poison Ivy and Batgirl.
Bud and Lou
Bud and Lou are a pair of spotted hyenas and the pets of Harley Quinn. Their names are references to the comedy duo of Bud Abbott and Lou Costello. Originally created for Batman: The Animated Series alongside Harley Quinn, Bud and Lou have since appeared in other forms of media following their debut. An alternate hyena pet, named Bruce, after Bruce Wayne, appears in the 2020 film Birds of Prey.
Romantic interests
Harley Quinn has had several love interests, the most notable being the Joker and Poison Ivy. Other love interests include Mason Macabre, a character created by Conner and Palmiotti. Plastic Man was initially intended to be a love interest for Harley Quinn by Kesel, but was not approved by DC.