Harley Quinn was first introduced as a villain

Villain

A villain is an "evil" character in a story, whether a historical narrative or, especially, a work of fiction. The villain usually is the antagonist, the character who tends to have a negative effect on other characters...

  on September 11, 1992, in the animated series Batman: The Animated Series

Batman: The Animated Series

Batman: The Animated Series is an American animated series based on the DC Comics character Batman. The series featured an ensemble cast of many voice-actors including Kevin Conroy, Mark Hamill, Efrem Zimbalist, Jr., Arleen Sorkin, and Loren Lester. The series won four Emmy Awards and was nominated...

, later adapted into DC Comics

DC Comics

DC Comics, Inc. is one of the largest and most successful companies operating in the market for American comic books and related media. It is the publishing unit of DC Entertainment a company of Warner Bros. Entertainment, which itself is owned by Time Warner...

' Batman

Batman

Batman is a fictional character created by the artist Bob Kane and writer Bill Finger. A comic book superhero, Batman first appeared in Detective Comics #27 , and since then has appeared primarily in publications by DC Comics...

 comic book

Comic book

A comic book or comicbook is a magazine made up of comics, narrative artwork in the form of separate panels that represent individual scenes, often accompanied by dialog as well as including...

s. As suggested by her name (a play on the word "harlequin

Harlequin

Harlequin or Arlecchino in Italian, Arlequin in French, and Arlequín in Spanish is the most popularly known of the zanni or comic servant characters from the Italian Commedia dell'arte and its descendant, the Harlequinade.-Origins:...

"), she is clad in the manner of a traditional harlequin

Harlequin

Harlequin or Arlecchino in Italian, Arlequin in French, and Arlequín in Spanish is the most popularly known of the zanni or comic servant characters from the Italian Commedia dell'arte and its descendant, the Harlequinade.-Origins:...

 jester. The character is a frequent accomplice and the girlfriend of Batman

Batman

Batman is a fictional character created by the artist Bob Kane and writer Bill Finger. A comic book superhero, Batman first appeared in Detective Comics #27 , and since then has appeared primarily in publications by DC Comics...

's nemesis the Joker

Joker (comics)

The Joker is a fictional character, a comic book supervillain published by DC Comics. He is the archenemy of Batman, having been directly responsible for numerous tragedies in Batman's life, including the paralysis of Barbara Gordon and the death of Jason Todd, the second Robin...

, and is also close to Poison Ivy, from whom she gained her immunity to poisons and toxins, as well as her advanced physical abilities.

The character was created by Paul Dini

Paul Dini

Paul Dini is an American writer and producer who works in the television and comic book industries. He is best known as a producer and writer for several Warner Bros./DC Comics animated series, including Star Wars: Ewoks, Tiny Toon Adventures, Batman: The Animated Series, Superman: The Animated...

 and Bruce Timm

Bruce Timm

Bruce Walter Timm is an American character designer, animator and producer. He is also a writer and artist working in comics, and is known for his contributions building the modern DC Comics animated franchise, the DC animated universe.-Animation:Timm's early career in animation was varied; he...

 and was originally voiced by Arleen Sorkin

Arleen Sorkin

Arleen Sorkin is an American actress, screenwriter, presenter and comedienne. Sorkin is known for portraying Calliope Jones on the NBC daytime serial Days of our Lives and for voicing Batman DC comic supervillainess Harley Quinn in Batman: The Animated Series and the many animated series and...

 in Batman: The Animated Series

Batman: The Animated Series

Batman: The Animated Series is an American animated series based on the DC Comics character Batman. The series featured an ensemble cast of many voice-actors including Kevin Conroy, Mark Hamill, Efrem Zimbalist, Jr., Arleen Sorkin, and Loren Lester. The series won four Emmy Awards and was nominated...

 and its tie-ins

DC animated universe

The DC Animated Universe is a fan term that refers to a series of popular animated television series and related spin-offs produced by Warner Bros. Animation which share the same continuity. Most of these series are adapted from DC Comics properties...

.