WARNING: The following article contains spoilers for Heroes in Crisis #3 by Tom King, Lee Weeks, Clay Mann, Tomeu Morey and Clayton Cowles, on sale now.

Harley Quinn turned 25 this year -- as a comic book character, that is. She made her comic book debut in 1993, in Batman Adventures #12, becoming the Joker's sidekick and love/hate interest. More recently, though, Harley had expanded beyond the Bat-verse and into the rest of the DC Universe proper, via her role as a member of the Suicide Squad.

RELATED: Superman Just Cemented Harley Quinn's Status as Top-Level DCU Fighter

Tom King and Clay Mann's Heroes in Crisis appears to be further expanding her influence. In Issue 2, she managed to get the drop on not only Batman, but Superman and Wonder Woman as well. And in Issue 3, she appears to coldly murder Wally West. Harley had already transformed from a second-rate villain into more of an antihero, but killing The Flash reverses that path and casts her as an outright villain. Is that perhaps Harley's next role, not only moving back to the role of a criminal, but also instated as one of the DCU's premier threats?

Harley's Humdrum History

In Batman: The Animated Series continuity, Harley was often cast as comic relief, in contrast to the Joker's comedic but darker tendencies. When her character was copied into the more serious mainstream DC continuity, she was given a little darker personality to match. Her presence was largely contained within the Batman family of titles, however, until DC's New 52 incarnation of Suicide Squad. She eventually graduated into her own series by Amanda Connor and Jimmy Palmiotti.

When she was in the shadow of the Joker, Harley never really stood out as a potential threat on her own. As a pseudo-hero, she likewise never had a place at the table among heroes like the Flash or Green Lantern. Whether one of the good guys or bad, the name Harley Quinn was never really bandied about with any kind of distinctiveness or significance. Although popular with readers, her character always seemed confined to the fringes of the DCU, never really playing a part in any truly major events.

NEXT PAGE: Harley Quinn is Still a Threat (and She's About to Become an Even Bigger One)

Harley in Crisis

Until now, that is. Harley has been given a preeminent role in Heroes in Crisis, and in fact has been one of the series' main characters thus far. She may or may not be responsible for the massacre at Sanctuary, but she is certainly being built up as having something to do with it. She's murdered one hero, and possibly many more. In the wake of those murders, she's returned to her traditional, black-and-red jester-like look -- a look associated with her days as a villain.

RELATED: Harley Quinn Becomes Batman's New Sidekick in February

It certainly seems as though Harley is being groomed to become a bad guy again. But not as the kooky, laughable Harley seen in Batman: The Animated Series. No, despite the return to her clown-like look, there's a darker edge to Harley now. She's the prime suspect in a series of superhero murders, and the primary heroes of the DC Universe no longer see her as a sidekick or a menace – she's now public supervillain No. 1.

Anyone who can deceive Wonder Woman, manipulate Batman, incapacitate Superman and murder The Flash can certainly no longer be called an antihero. Or even a second-rate villain. No, at this point, Harley Quinn has proven herself capable as a premier supervillain of the DC Universe, and, whatever happens going forward, its heroes are going to have to treat her as such.

A New, True Threat to the DCU?

Harley's latest transformation fits into the trend of publishers finding ways to push their otherwise sideline characters into the forefront. Batman, for instance, while always DC's most popular character, wasn't of much use in continuity-altering events like Crisis on Infinite Earths. But come Dark Nights: Metal, Batman moved from the rooftops of Gotham into the very fabric of the multiverse -- two multiverses, actually.

Likewise, Marvel Comics has found a way to further capitalize on their most popular mutant, Wolverine. Once confined to the X-Men's corner of the Marvel Universe, Logan joined the Avengers for a time and is now known to eventually wield the power of the Phoenix Force. Marvel's friendly neighborhood Spider-Man also joined Earth's Mightiest Heroes at one point. Spidey now crisscrosses the multiverse from time to time whenever the rest of the Spider-Verse comes calling -- quite a leap from hanging out in Queens.

There are already plans afoot to send Harley to Apocalypse, so she's certainly poised to make a far bigger name for herself. It's not like there isn't precedent for it.

Harley's hammer will be putting a lot more dents in the DCU pretty soon.