There have been many different iterations of Harley Quinn across all forms of media, but Batman: Arkham played a huge part in changing the character from her initial henchwoman role. Harley was originally intended to make a one-time appearance in Batman: The Animated Series, but she became so popular that she was made a permanent member of the cast. However, it wasn't until her appearance in Batman: Arkham Asylum and the subsequent games that Harley Quinn became the iconic character she is today.
The Batman: Arkham games gave villains like Harley Quinn a chance to shine as their own dynamic characters with emotional depth and some serious skills. In Batman: The Animated Series, Harley was included as the comic relief, but she clearly had much more to offer. Not only did the Batman: Arkham series change Harley's look, but it revamped her personality as well.
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Before Batman: Arkham City, Harley Quinn was only played by one voice actor: Arleen Sorkin. Harley was inspired by Sorkin, but she also needed to evolve from her origins to develop into a true challenge for Batman. Throughout the Batman: Arkham games, Harley becomes more and more twisted and presents a greater threat to Batman with each title. The differences between each Harley in the games have inspired a completely new Harley Quinn in movies, comics, and all forms of media.
Harley Quinn first appeared in episode 22 of Batman: The Animated Series, «Joker's Favor.» Harley was created as a secondary comic relief character who was blindly devoted to the Joker. She had a few spinoff storylines, but nothing serious or show-altering. Harley also didn't have much in the way of character development
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