The very successful Tim Burton series of Batman films were one of the main impetuses for the creation of this series, and executive's hoped to capitalize on their success. The design for the Penguin was based on the design of the character as it appeared in the then-current and highly successful Batman Returns, which cast Danny DeVito as a physically deformed and emotionally scarred man with fingers fused into a flipper-like arrangement, as opposed to the comic counterpart, who(although only about 5' tall and sporting a prominent aquiline nose) was a still just a regular man. Catwoman was likewise turned into a blonde woman to match Michelle Pfeiffer's character, as opposed to her darker-haired appearance in the comics. Both characters were returned to their original comic appearance after the series was revamped into The New Batman Adventures.
Well, in spite of his physical appearance, the Penguin is written as a civilised criminal in a tail coat and top hat. He just happens to also look a little freakish (though nowhere near as much as the film version does). It's ambiguous where his name comes from; probably a combination of his obesity and deformity and his clothes (which is sort-of the same as in the comics). The important thing is how he acts, and if anything this one is even more civilised than the comic book one.
Several episodes were actually improved because concern over the detail on-screen in some scenes forced changes to the animation, giving them much more emotional power. Dick Grayson's parents falling from the trapeze showed his parents swinging off screen, with a frayed rope swinging back in and everyone gasping in shock. If they showed any more, it would not have been as effective. "Over the Edge" contains another instance. Apparently, when Batgirl is thrown off of City Hall to her death we were originally going to see a police car pull up and then her body would land on the hood. When this was deemed too extreme, Timm redesigned the sequence as though the viewer was in the back seat of the car when the impact occurred. This has the effect of making things far more disturbing. Similarly, "I Am The Night" originally wanted to show Robin getting shot on camera. The network made them change this, so they picked Gordon and did not actually show the shooting. They all agreed this made the scene more powerful.
Richard Moll provided both the normal and gravelly voices for Harvey Dent/Two-Face.
And the Batcomputer.
And a random security guard in the pilot.
George Dzundza, known to Law & Order fans as Max Greevey, voiced Scarface and in the SubZero movie, Gregory Belson. He also voiced the Ventriloquist (Scarface's main personality) and in the episode "The Laughing Fish," G. Carl Francis. And these weren't his only roles in the DCAU as Perry White proves.
Adam West plays the Gray Ghost from the episode, "Beware the Gray Ghost." From the moment the episode was written, they knew they wanted Adam West as the part; otherwise, the episode would have been scrapped.
Recurring Gotham news reporter Summer Gleeson is Renamon.
B:TAS is notable for featuring a number of Star Trek actors, most notably Kate Mulgrew as Red Claw and John de Lancie as one of the Penguin's henchmen in "Blind as a Bat."
From episode “Baby-Doll,” Alan Young), Alison LaPlaca (best known for role as acid-tongued yuppie Linda Phillips on Duet and its spin-off, Open House), Judy Strangis (best known for her roles in Series/Room222 and in Electra Woman and Dyna Girl), Robbie Rist, and Jason Marsden played the fictional family Mr. and Mrs. Daly, sister Suzy, brother Brian and cousin ‘Spunky’ Spencer in fictional show Love That Baby to the titular former child star Mary Dahl, also voiced by Alison LaPlaca.
For RoboCop fans, you might recognize Daniel O'Herlihy (The Old Man) as Grant Walker and Robert DoQui (Sgt. Reed) as the doctor who treated Harvey Dent after the accident that helped turn Harvey into Two-Face.
Irony As She Is Cast: The Penguin squawks out a grating accompaniment of I, Pagliacci in "Birds Of A Feather". His voice actor Paul Williams is actually an acclaimed singer/songwriter with notably smooth, melodious vocals(as can be heard in the Penguin's speaking voice).
The Other Darrin: Alfred was voiced by Clive Revill for a handful of episodes, then by Efrem Zimbalist Jr. when Revill left to fulfill a theater commitment. A number of villains also were recast for the New Batman Adventures series including Scarecrow, Baby Doll, and Killer Croc. Penguin and Bane were recast in the Batman: Mystery of the Batwoman film. Excluding Batman Beyond, Batgirl went through three actors during the course of the series — Melissa Gilbert in the early episodes, Mary Kay Bergman for her later appearances and Tara Strong for the revamped episodes in The New Batman Adventures.
The Other Marty: Tim Curry was originally cast as the Joker, but he was replaced by Mark Hamill (who had already appeared as one-time villain Ferris Boyle) because Curry's Joker voice was too strenuous to produce.
Promoted Fanboy: Mark Hamill was cast as his favorite character. By sheer enthusiasm. Bonus points for becoming one of the most famous portrayals of said character.
What Could Have Been: Tim Curry was originally cast to be The Joker, but Paul Dini states he was let go due to the physical strain his Joker voice put on his throat. You can actually hear his Joker laugh (somewhat modulated) in the episode "Be A Clown", coming from an animatronic clown.