One of the series' best-known inventions is the Joker's assistant, [[Harley Quinn]], who became so popular that DC Comics later added her to mainstream comic book continuity. [[Penguin (character)|The Penguin]] underwent change for the series; his appearance was remodeled after the version seen in ''[[Batman Returns]]'', which was in production simultaneously with the series' first season. New life was also given to lesser-known characters for the series, such as the [[Clock King]]. In addition, dramatic changes were made to other villains such as [[Clayface]] and [[Mr. Freeze]], the latter of whom was changed from a gimmicky [[mad scientist]] to a [[tragedy|tragic]] figure whose "frigid exterior [hid] a doomed love and vindictive fury".
==Characters==
The [[Joker (character)|Joker]]'s accomplice [[Harley Quinn]], Gotham City police detective [[Renee Montoya]], the vigilante [[Lock-Up (comics)|Lock-Up]], former actor Simon Trent, brainwashed comedian-turned-supervillain Condiment King, and ninja Kyodai Ken are original creations who became characters in the comics. Older villains that were lesser known from the comics, such as [[Count Vertigo]], the [[Weasand (comics)|Mirror Man]] and the [[Clock King]], were modified for the series in both appearance and personality. Other original antagonists were created, such as Roland Daggett, Red Claw, the Sewer King, Boss Biggis, Grant Walker, H.A.R.D.A.C., and Emile Dorian, but to little acclaim, and did not make any appearances outside the series, though Daggett was re-imagined as businessman John Daggett for ''[[The Dark Knight Rises]]''.
Though the Joker's origin is never shown in the series (one of only two villains in the series who never got an origin episode, the other one being [[Penguin (character)|The Penguin]]), some of his past is seen in the feature film ''[[Batman: Mask of the Phantasm]]''. In flashbacks, he is shown before his accident but does not speak or is referred to by name. His potential real name, '''Jack Napier''' (the same name of [[Jack Nicholson]]'s [[Joker (Jack Napier)|version of the character]] from [[Tim Burton]]'s [[Batman (1989 film)|1989 film]]), is established in the episodes "Dreams in Darkness" when it is spoken by Dr. Bartholomew and in "Joker's Wild" where it is written in a dossier. The use of this origin was due to the show being heavily patterned after the success and influential tone of Tim Burton's film. However, when ''[[The New Batman Adventures]]'' began, during the era of [[Joel Schumacher]]'s films, Joker's origin was retained but his identity was retconned as being merely one of many aliases as seen in the episode "Beware the Creeper", meaning his true identity is still unknown. This reflected the efforts of the writers to put the character back in line with his conflicting multiple origins from the comics.
While the use of this origin was based on the Jack Nicholson version, [[Mark Hamill]] was given the note "Don't do Nicholson" before his audition.<ref>Archived at [https://ghostarchive.org/varchive/youtube/20211211/dZLpDvQ6vFI Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20200617011200/https://www.youtube.com/watch?v=dZLpDvQ6vFI Wayback Machine]{{cbignore}}: {{Cite web|url=https://www.youtube.com/watch?v=dZLpDvQ6vFI|title=Batman The Animated Series | The Heart of Batman Documentary Livestream | Warner Bros. Entertainment|via=www.youtube.com}}{{cbignore}}</ref> During production, Hamill asked the production team (consisting of Timm, Radomski, and Romano) if he could play one of the villains after a small appearance as Ferris Boyle in "[[Heart of Ice (Batman: The Animated Series)|Heart of Ice]]". Even though [[Tim Curry]] had already recorded a few episodes, Hamill was given the part after Curry developed bronchitis and departed the series. Hamill, who found himself to be the biggest fan of the Batman comics among the cast, credited the laughs he had honed on stage in ''[[Amadeus (play)|Amadeus]]'' with landing him the role.<ref name="HR25"/> He worked to craft a multifaceted laugh for the Joker that could change to reflect the Joker's current mood, likening it to a musical instrument.<ref name="auto">[Batman: The Animated Series: The Legacy Continues, Voices of the Knight, Arkham's Files The Joker]</ref> When recording his lines with the other actors, Hamill would stand while the other actors would remain seated to invest himself in the role. Hamill's interpretation of the Joker is considered to be groundbreaking for the voice-acting industry, and led to Hamill having an enormously successful voice-acting career.<ref name="auto"/> Of the many influences for his performance, including [[Jay Leno]] and [[Howard Cosell]], Hamill cited [[Claude Rains]]' performance in the film ''[[The Invisible Man (1933 film)|The Invisible Man]]'' (1933).<ref>{{Cite web|title=Many, many influences, but it started with the brilliant Claude Rains as The Invisible Man-always a favorite of mine|url=https://mobile.twitter.com/hamillhimself/status/655463730688331776|access-date=May 21, 2021|website=Twitter|language=en}}</ref><ref>{{Cite web|url=https://www.syfy.com/syfywire/mark-hamill-channeled-the-invisible-man-and-jay-leno-as-inspiration-for-the-joker|title=Mark Hamill channeled the Invisible Man and Jay Leno as inspiration for The Joker|first=Josh|last=Grossberg|date=March 29, 2018|website=SYFY WIRE|access-date=October 22, 2020|archive-date=September 26, 2020|archive-url=https://web.archive.org/web/20200926113235/https://www.syfy.com/syfywire/mark-hamill-channeled-the-invisible-man-and-jay-leno-as-inspiration-for-the-joker|url-status=dead}}</ref>
Aside from creating characters that crossed over into the main line of DC Comics, several of the series' reinterpretations were carried over as well. [[Mr. Freeze]] was revised in the comics to emulate the series' tragic story, the success of which actually compelled DC to bring the character back after "killing" him off some years earlier. [[Clayface]] was revised to be much more similar in appearance to his animated counterpart; and Two-Face's double-sided, black-and-white suit has become a common appearance for the character.
===Bruce Wayne / Batman===
At the age of eight, Bruce Wayne, the son of billionaire philanthropists, witnessed the murder of his parents, Thomas and Martha, during a mugging on the street. The event left him traumatized and mentally scarred for the rest of his life. Bruce was placed in the care of his family's butler, Alfred Pennyworth. Over the years, Bruce slowly turned the pain and trauma he sustained into a burning fuel for a lifelong obsession, as he underwent rigorous training in mental and physical conditioning. Having observed the rampant crime and corruption in Gotham City, Wayne swore an oath to dedicate his entire life to fighting crime, in a bid to avenge the murder of his parents, while being guided by his self-enforced moral code to never kill and to refrain from using firearms (which he detested, as the tool of his parents' murder). Inspired by his childhood fear of bats, Wayne reasoned that he could use that fear against the criminals he faced, and adopted the identity of 'The Batman', a feared, near-mythical bat-like vigilante.
[[Kevin Conroy]] used different voices to distinguish between his portrayal of Bruce Wayne and Batman, a tactic used previously by [[Michael Keaton]] in [[Tim Burton]]'s live-action films.<ref name="Murphy">{{cite web |last=Murphy |first=Joel |date=October 1, 2009 |title=One on One with Kevin Conroy |publisher=HoboTrashcan |url=http://www.hobotrashcan.com/2009/10/01/one-on-one-with-kevin-conroy}}</ref> Conroy based his dual-voice performance on the [[The Scarlet Pimpernel (1934 film)|film adaptation of ''The Scarlet Pimpernel'' (1934)]].<ref name="HR25">{{cite magazine|url=https://www.hollywoodreporter.com/heat-vision/batman-animated-series-hirings-firings-last-minute-changes-1035120|title='Batman' at 25: Hirings, Firings and Other Last-Minute Changes Behind the Animated Classic|magazine=The Hollywood Reporter|date=September 5, 2017|access-date=July 17, 2018|author1=Burton, Byron |author2=Couch, Aaron}}</ref>
===Other characters===
Other antagonists that appeared in the series included classic villains such as [[Poison Ivy (character)|Poison Ivy]], [[Catwoman]], the [[Riddler]], [[Two-Face]], the [[Mad Hatter (DC Comics)|Mad Hatter]], [[Ra's al Ghul]], [[Talia al Ghul]], [[Man-Bat]], the [[Penguin (character)|Penguin]], the [[Scarecrow (DC Comics)|Scarecrow]], [[Killer Croc]], [[Bane (comics)|Bane]], the [[Ventriloquist (comics)|Ventriloquist and his dummy Scarface]], [[Hugo Strange]] and [[Tony Zucco]]. Friends and allies of Batman featured in the show not previously mentioned include [[Alfred Pennyworth]], [[Harvey Bullock (comics)|Harvey Bullock]], the [[Beware the Gray Ghost|Gray Ghost]] (an original character created by the series to portray Bruce Wayne's childhood hero and crimefighting inspiration, voiced by [[Adam West]], the actor who had played Batman in the [[Batman (TV series)|1960s ''Batman'' series]]), [[Lucius Fox]], and [[Leslie Thompkins]].
== Characters ==
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