- "We're bad guys, it's what we do!."
- — Harley Quinn
Harley Quinn, born Harleen Frances Quinzel, she is also known by her alias Barbara Kean, is a female Human who was a psychiatrist at Arkham Asylum who was turned into a insane criminal and the ex-girlfriend of The Joker. She is the Joker's on again and off again sidekick. She is Selina Kyle's righthand woman and works with Selina and her husband Typhuss as a member of the Sirens.
Harley initially appeared to be a kind, caring, selfless and moral individual. Unknown to anyone at the time, Harley is (secretly) mentally unstable. After she was forced to kill several civilians by The Joker, Harley's unstable nature had awoken.
Since her psychotic break, Harley has openly become arrogant, aggressive, violent, immoral, unstable and delusional.
After Harley comes out of her coma, she apparently has guilt and remorse for her actions, and was apparently horrified at what she had become/done. Although she claimed she was sane after being released from Arkham, she seemed to suffer another psychotic break after Jim rejected her.
Her latest personality is not without affection or care for those close to her, but she is also shown to be cold and conniving. She has little respect for authority of any kind and is prone to a violent and sadistic nature.
- Peak of human physical condition Harley Quinn, as a highly skilled and experienced supervillain and gymnast, is in top physical condition (from frequent villainous escapades with her boyfriend the Joker) for a woman her age, to the point that she could hold her own against the formidable hechmen of Penguin. She was notably however, far weaker than her nemesis Batman, who subdued her without much effort.
- Expert hand-to-hand combatant/Martial artist: Harley Quinn is a highly skilled and formidable armed and hand-to-hand combatant and martial artist, managing to seriously injure 5 guards. She also quickly overpowered 2 far larger men in rapid succession (with nothing but her agility, combat skills and baseball bat). However, she was swiftly defeated by Batman (with the latter knocking her out with a single mighty punch).
- Expert acrobat: Harley Quinn, as a former gymnast, is shown to be highly skilled in various acrobatics, including pole dancing and other agile maneuvers, often incorporating agile moves while fighting opponents, notably able to flip over the monstrous The Penguin when he managed to get a hold of her (thus twisting herself out of his grasp), and to easily dodge slashes from his daggers.
- Expert markswoman: Harley Quinn, while not nearly on par with Deadshot, is nonetheless a highly skilled markswoman, landing several headshots on some of Penguin's guards.
- Gifted intelligence: Harley Quinn, while still Harleen Quinzel, was (and likely still is) exceptionally smart, having been an excellent academic achiever in high school, which earned her a full scholarship to the prestigious Gotham State University, where she would go on to write a very successful graduate thesis. Harley's intellect extends itself to her psychological, tactical and deception skills.
- Expert psychologist: Harley Quinn, while still Harleen Quinzel, was a highly skilled psychologist, majoring in psychiatry at Gotham State University, with her psychology graduate thesis being a huge success, and allowing her the opportunity to work as a psychologist at the infamous Arkham Asylum itself. Even after being rendered psychopathic by the Joker, Harley shows at least traces of her psychologist expertise, being able to make swift breakdowns of the psychological profiles of El Diablo, Killer Croc, and Katana, knowing exactly what to say in order to get under their skin. Hence, she even proudly proclaims to Rick Flag that "[she] is known to be quite vexing."
- Expert tactician: Harley Quinn, while not quite on par in this regard with her boyfriend Joker, is nonetheless highly skilled with improvising criminal activities.
- Expert deceiver: Harley Quinn is a highly skilled deceiver, thus when Deadshot pretended to shoot at her, she convincingly pretended to have been killed only to reveal that she is still alive and later on, managing to trick a woman criminal into thinking that she was about to swear allegiance to the latter, and to subsequently use that distraction to suddenly cut open the woman' chest with a sword, exposing and pulling out the supervillain's vulnerable heart.
- Pathological indomitable eill: Harley Quinn (much like the Joker) possesses an obliviousness to danger that makes her invulnerable to fear and intimidation, which are usually Batman's greatest weapons in combat.
- Chiappa Rhino 60DS: Harley sports a customized Chiappa Rhino 60DS, 6 cylinder magnum revolver, utilizing it for long-ranged combat. She carries it in a black leather holster slung under her arm.
- "Good Night" bat: Harley carries a personalized wooden baseball bat for melee combat, with "Good Night" being written down the side of it. She does have an urge to play with it, one example being when she pretends she's holding a shotgun.
- Harlequin suit: Harley's original suit which she wore shortly after getting corrupted by the Joker.
- Knife: Harley carried a knife that she tried to use to stab Batman with.
- Mallet: Harley carried a personalized wooden mallet which she used during her villanous escapades with her boyfriend the Joker. When the squad was given their old equipment, she almost brought the mallet to Midway City with her but chose to bring her baseball bat instead.