The DC Animated Universe collected many of the publisher's best superheroes and supervillains. Batman kicked things off with The Animated Series in the early '90s and it arguably gave the DCAU their best villain in The Joker.
The Joker is the Dark Knight's most notorious Rogues' Gallery member, and Mark Hamill's portrayal of the Clown Prince of Crime did well to hold up that legacy. He has several memorable quotes across his appearances in the universe that are testaments to his status as its greatest threat.
His Warped Infatuation With Batman
"Without Batman, Crime Has No Punchline."
Joker and Batman's dynamic is one of the most iconic in the superhero genre, and The Animated Series gave many compelling demonstrations of it. In one episode, Batman's arguable greatest supervillain becomes saddened by the idea that someone else finished the Dark Knight other than him.
BTAS was exceptional for how it handled the perfect balance of darkness with the superhero genre's inherently whimsical nature, with this quote still speaking volumes about the Joker's warped sense of infatuation for Batman. At the end of the day, he constantly commits these atrocities in a desperate attempt to get Batman's attention and give the villain "purpose."
Taunting Batman's Weakness
"Oh, Batman. If You Had The Guts For That Kind Of Fun, You'd Have Done It Years Ago."
Return of the Joker -- in the Batman Beyond series -- is one of the best animated Batman movies to date. It also featured one of the most haunting depictions of the Joker in the DCAU and the most mesmerizing performances by Mark Hamill as the villain. One of the most tragic moments in the universe was the extended flashback detailing Tim Drake's tragic torturing at the hands of the Joker.
This nearly pushes the Caped Crusader over the edge and he threatens to "break" him, and the Clown eerily taunts that he's more than happy to call his bluff. It's a single dark line of dialogue, but one with resonating ripple effects across the brutal history of their twisted relationship.
Joker's Unintentional Humor
"I'm Crazy Enough To Take On Batman, But The IRS? No, Thank You!"
While he's an undeniably maniacal and heinous villain, part of the allure of the character that makes him such a compelling antagonist is his humorous side. It gives an added facet to the Joker's personality that keeps him so interesting and enduring across every entertainment medium over the last 80-plus years.
Perhaps one of his most famous lines in the DCAU was in "Joker's Millions," where he acknowledges his insanity while simultaneously asserting he's not so crazy that he'd take on the IRS over Batman. It's a great comedic quote and served as a clever and meta tongue-in-cheek joke.
Joker's Ability To Toy With Batman Psychologically
"Behind All The Sturm And Bat-O-Rangs, You're Just A Little Boy In A Playsuit, Crying For Mommy And Daddy!"
Though Batman is perhaps the DCAU's greatest superhero, the Joker still knows how to hit a nerve with him. That says quite a bit about the Joker as a serious villain, as it takes magnitudes of psychological warfare to get to the Batman. In Return of the Joker, the Clown Prince of Crime makes the most of his sadistic magnum opus to cause maximum emotional damage to Robin, Batman, and Batgirl.
Joker forces them to watch his cruel drumroll to Tim's grim reinvention and mocks the Bat-family head in the process. Alone, this taunt may not have amounted to much, but having Batman be his "captive audience" for the reveal of his brutalized adoptive son makes this line hit harder.
His Manipulative & Ironic Nature
"It's Only Natural You'd Be Attracted To A Man Who Could Make You Laugh Again."
Alongside the likes of the aforementioned "Jokers Millions," "Mad Love" is among the best episodes of The New Batman Adventures. It's also one of the most iconic Harley Quinn episodes, with the episode showing Joker's cruel and ironic manipulative nature. It shows the origin of how Joker wormed his way into Harley's vulnerable state of mind and the villainous pair's mental weaknesses.
This line could be argued as having a double meaning, as it demonstrated how conniving the Joker can be, but can be seen as ironic since Batman is the one he's persistently "attracted" to who "makes him laugh." Another example of the villain's twisted sense of purpose.
Joker's Deep-Rooted Obsession With Batman
"You're Not Batman!"
The grand climax of Return of the Joker saw the regenerated supervillain go toe-to-toe with Terry McGinnis' iteration of Batman. Though this scene is also an argument in favor of Terry's Batman as the DCAU's best hero, this simple yet thunderous line is also a good example of the depths of Joker's obsessive villainy.
Despite this being a satisfying and rare moment of weakness for the Clown, it shows how deep into his sickening psyche his obsession for Batman goes. Terry manages to goad the Joker in exposing his biggest downfall: that even in the distant future, he's still pathetically hungry for Bruce Wayne's audience and "approval," given how he sees Wayne as the only Dark Knight.
Sadistic Brand Of Humor
"Oops! No, I Wasn't! That's Also How We Did It In My Day!"
Joker's earlier scenes from Return of the Joker are a suitably grand and grim way to re-introduce him. Through psychological technology and Tim Drake's body as a host, the villain finds himself in Terry's Gotham City of the cyberpunk future.
Joker hires the gang of his cultish worshippers as his new underlings where she shows off his unique brand of sadistic humor. Without hesitation, he plays on the fears of his cronies and kills one as soon as Joker feels annoyed and needs to make an example. Regardless of the era, Joker is a relentless force of nature whose callousness knows no bounds.
The Rampant Narcissism
"And Don't Call Me Puddin'."
In "Mad Love," Joker's full-blown narcissism is on display, along with Harley Quinn's hopeless desperation. He's furious that Harley created a better plan to kill Batman than him, though, the superhero ultimately plays on both of their faults to still win the day. Earlier in the episode, Joker throws a temper tantrum as he struggles to think of a new scheme and takes it out on Harley.
The line barking at her to stop calling him his signature "pet name" is a shallow one, but that's exactly why it's such a good showcase for his dangerous ego. Joker's rampant narcissistic tendencies are both a threat and a baked-in feature of his weaknesses.
His Limitless Capacity For Cruelty
"Oh, What The Heck, I'll Laugh Anyway."
The extended flashback sequence was an impressive showcase for how Batman and his vast mythos could be explored even in the realm of mainstream animation, and the way Joker was immaculately written is among RotJ's biggest strengths.
Torturing Tim was the darkest thing he'd ever done to the Bat-family, and this quote is a good representation of how bleak things are when the villain gets his way. He makes Batman watch his stomach-churning "home video" of how he systematically dismantled Robin's mind, and had the gall to laugh in his face.
Joker Will Turn On Anyone At Any Time
"Remember, It's Not The Fall. It's The Sudden Stop."
Part of what makes Joker so dangerous is his unpredictability. Plus, the Clown Prince Crime serves no one but himself. In an episode of BTAS, where Hugo Strange nearly reveals Batman's secret identity, the villains he hired begin to turn on him once it becomes evident he failed. Among them, unsurprisingly, is the Joker.
The group takes Strange on a plane where the villain dangles him out the door, giving a chilling threat of what's the real fear of falling from great heights. It's certainly a play on his name and motif, but the Joker is a "wild card" in every sense of the term.