Stop us if you've heard this one before. Girl falls for a famous, crazy, murderous, psychopatic Clown Prince of Crime. Girl, in turn, starts wearing red and black, becoming the Clown Princess of Crime. And, in the meantime, girl becomes even as popular, if no more so, than the guy, and strikes off on her own.

Sounds familiar? That's pretty much the tale of DC Comics' very own Harley Quinn, a character who is celebrating her 25th anniversary this month. Although it might sound far-fetched, the court-jester clad villainess only took a third of the time to reach a level of popularity to match, and at times even outshine, her significant other.

RELATED: Paul Dini Wishes Harley Quinn a Happy Birthday

If you take the time to walk into a comic book store or a toy store, if you simply decide to visit DC's website or check out what movies the comic book company is currently developing, you might notice a familiar theme: Superman, Batman, Wonder Woman? Check -- that's a given, since these characters are DC's Trinity, the company's three biggest characters, recognized and cherished the world over. But these past few years has seen the rise of a fourth member in DC's pantheon, one who emerged from the pack to become just as popular as the world's biggest superheroes. Indeed, Harley Quinn managed to creep up on everyone and somersault her way to become, as Jim Lee once put it, the fourth pillar of DC Entertainment. But how did it all happen?

Harley breaks the Joker out of Arkham

Harley Quinn was created by Batman: The Animated Series masterminds Paul Dini and Bruce Timm, making her very first appearance in September 1992 in the episode “Joker's Favor.” It was there that she was introduced as the black-and-red clad henchwoman of the Joker, one who was enamored with the clown even while being constantly rejected and abused by him. No matter what he did, she loved her “puddin',” sticking to his side through thick and thin, through rejections and death-defying betrayals. Harley quickly became associated with the Joker, and would appear in nearly every episode he was featured in. It only took a year for her to make the jump from the animated screen to the comic page, first appearing in The Batman Adventures #12 in September of 1993, a comic series set in the Batman: TAS universe.

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How Harley Quinn Conquered the DC Universe

It was a few more years, however, before she made the jump to the regular DC Universe in 1999’s Batman: Harley Quinn, a tie-in to the year's big Batman crossover event. From then on, she was able to trade wits with any character she came across, from Superman and Wonder Woman, to Power Girl and Lobo. Thanks to a continuous but unassuming presence in the main DCU continuity, Harley but her very own fan-following, but it was never anything world-shattering. She starred in her very own series by Karl Kesel and Terry and Rachel Dodson from 2001-2003, and developed a special friendship with both Poison Ivy and Selina Kyle. Together, the trio became known as the Gotham City Sirens during the "Batman Reborn" era of 2009.

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In a way, 2009 was the year that Harley's popularity began to spike exponentially. Although she had always been recognizable to fans of the Batman cartoons and comic book readers, this was when she entered an all-new medium: video games.

Harley Quinn from Arkham Asylum

Batman: Arkham Asylum, a game developed by Rocksteady Studios, gave players the opportunity to become the Batman and spend one incredibly long night trapped in Arkham Asylum. It proved incredibly popular with both casual and hardcore gamers, and propelled Batman's star status even further into the stratosphere. Naturally, with the game taking place in Arkham Asylum, one of the starring villains was Harley Quinn. Ditching her traditional costume, this Harley wore a classic nurse's outfit, albeit one twisted to adhere to her color scheme of red, black and white. It was the first time fans of the character saw her in a new costume, and for many others, their very first introduction to the loony, goofy, playful-yet-dangerous villain.

Instantly, the character struck a chord with the audience, and as the game's popularity grew, so too did Harley's. Walking around comic book conventions at that time, you could clearly see a rising number of Harley Quinn cosplayers dressed in the new nurse's costume. And she would only get bigger from there; in 2011, the sequel, Batman: Arkham City, took the gaming world by storm. Bigger and badder than its predecessor in every possible way, the game gave an even larger role to Harley Quinn, who this time around had a far more proactive part to play. Where before she was more a presence that bordered on nuisance, in Arkham City, despite Harley's never-shifting allegiances, she had a gang of her own, and even a playable story pack. Once again, her popularity grew, and her new, more tactical costume became more and more recognizable.

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Welcome to the Suicide Squad, Harley Quinn

As it turns out, Arkham City was only the first punch of a one-two combo. 2011 would also see a complete overhaul of DC Comics' entire line of titles with the arrival of the New 52. A total relaunch of DC continuity, the New 52 was the publisher's attempt at modernizing its characters while streamlining its narrative to make it approachable for new readers. For that reason, we got new origins and costumes for many established characters, and new directions for many titles. One of the biggest changes involved Harley Quinn; no longer was she the full bodysuit jester outfit-wearing character readers knew for nearly two decades, and no longer was she simply the Joker's girlfriend. Introducing a new color scheme of red and blue as part of a far more revealing outfit, Harley Quinn joined Amanda Waller's Task Force X in the Suicide Squad title, along with Deadshot, Captain Boomerang, El Diablo and King Shark.

Suicide Squad New 52

It was here that Harley began to take the final steps in her climb to her current level of popularity, proving that she was not just the one thing people expected her to be. She wasn't defined just by the company she kept (read: The Joker). She had grown into her own, proving that her very special kind of crazy could be an asset to a team. As a member of the Suicide Squad, Harley slowly began to enter a new phase; no longer was she a criminal -- she was an anti-hero.

Not long after that, Harley once again became the star of her very own title, Harley Quinn by Amanda Conner, Jimmy Palmiotti, Chad Hardin and a slew of other brilliant artists. This quirky series became a hit of its own, showing a more lighthearted, fun side of Harley, but without losing sight of the crazy, the violent and the hilariously strange.

RELATED: Why Is Harley Quinn So Popular? Kevin Conroy Has An Idea

The title proved to be a strong addition to DC's line of titles, with sales that rivaled or surpassed the rest of DC's publishing line. Her supporting cast grew, as Harley's status as one of the leading stars of DC's pantheon began to take form, and along the way, several successful miniseries spun directly out of it, like Harley's Little Black Book, Harley Quinn and Power Girl and Harley Quinn And Her Gang of Harleys. The main title remains a DC Comics mainstay, while more and more Harley Quinn merchandise has begun to pop-up in stores around the world. Action figures, statues and collectibles, costumes, makeup and accessories -- there's practically nothing a Harley fan can't find that isn't emblazoned with her image or iconography.

A third Arkham game arrived in 2015, Arkham Knight, a sequel that featured Harley Quinn in an even bigger role with, once again, a different costume. Harley, at this point, was on the cusp of becoming a worldwide sensation. In fact, a year later, in August 2016, Warner Bros.' and DC Entertainment would release Suicide Squad after a massive marketing campaign that greatly focused on Harley Quinn (and Joker) before the movie ever hit theaters.

To no one's surprise and everyone's ultimate satisfaction, Margot Robbie lit up the screen in the movie, proving to be the perfect actress to bring Harley to live-action. By the time the credits rolled on the film, people who weren't familiar with the character, who had no idea about comics or cartoons or video games, found themselves Harley Quinn fans. The character's crazily cheerful and murderous attitude struck a chord with the audience, a bright spot in a film that otherwise received mixed reactions.With that, Harley's position was sealed. Her movie costume became a convention and Halloween staple, she had her very own lines of statues and action figures and, perhaps most tellingly, her very own wall of merchandise in chain stores like Hot Topic.

RELATED: Joker and Harley Quinn Movie Reportedly in Development at WB

Now, there are rumblings of Robbie's Harley starring in a Gotham City Sirens movie, a Joker and Harley Quinn movie and Suicide Squad 2 which is actually more movies than Superman currently has in development. She's still starring in her own solo comic book title amid the DC Rebirth relaunch, and one of the main stars of the Suicide Squad series. This year, she even usurped the annual Batman Day celebration on September 23, complete with her very own specially covered comics, masks and giveaways.

When it comes to Harley Quinn, there's just no slowing down. She might have debuted as nothing more than a knock-knock joke -- but she kicked the door down, and built her very own house.