If you've been reading comics for a while, you know that status quo changes are the norm in this industry. From heroes turning into villains to going back to issue #1 to a change in the multiverse, these shake ups are to be expected every few years to reinvigorate a lineup of books. Most importantly, changes in the status quo are a great way to get readers to buy more comics. Just ask DC, which was in a major slump in terms of sales until it launched its Rebirth, bringing back some of the classic elements of the old DC Universe that had been erased during the New 52 relaunch -- itself a major shakeup unlike any other in the company's history.

RELATED: 15 Times Marvel Changed Its Movie Universe (Without You Noticing)

DC has changed bits and pieces of its continuity for years, dating all the way back to Crisis on Infinite Earths and even before that. There's never been a time when the company wasn't tweaking something in order to freshen up a book here and there. Rebirth is just the latest example of a major change in the status quo. In the list below, you'll find recent changes big and small. Some of them may even shock you!

15 WATCHMEN JOIN DC UNIVERSE

Doctor Manhattan on Mars in Watchmen

This was the biggest reveal in DC Universe: Rebirth #1 by Geoff Johns: Dr. Manhattan is the reason the New 52 timeline happened in the first place. After Barry Allen went back in time to save his mother in Flashpoint, which was also written by Johns, he messed up the present and was forced to correct his mistake. But even after he changed everything back in the past, the present was still quite a bit different. You see, the god-like Dr. Manhattan stepped in and stole ten years from the DCU timeline, dooming several characters (such as Wally West) to never having existed at all!

While Dr. Manhattan's return is setting him up to be the biggest villain in the current DCU, he sets an even bigger precedent: Alan Moore and Dave Gibson's Watchmen is now part of DC continuity. Even the Comedian's iconic, blood-splattered button has appeared in the Batcave!

14 JAMES GORDON: BATMAN

James Gordon as All New Batman

This was pretty unexpected: Bruce Wayne had seemingly died in a final battle against the Joker, and Gotham was left without a protector. That is, until Geri Powers had the brilliant idea of recruiting former police commissioner James Gordon to take over as the first GCPD-sanctioned Batman. Decked out in a very slick Batsuit and a giant mech suit, Gordon proved to be a very formidable successor. At least until a new villain named Mr. Bloom came to town. Then Gordon got his butt handed to him.

"Superheavy," the final arc in Scott Snyder and Greg Capullo's excellent Batman run, is all about why Gotham needs Batman to be an inspiration and why only Bruce can truly don the cape and cowl. But along the way, we also got to witness one of the coolest shake ups in recent comics history.

13 YOUNG ANIMAL

Doom Patrol Young Animal

Gerard Way's Young Animal imprint has been one of the great delights in DC's modern history. So far, the line has reintroduced a ton of classic characters to new audiences with some pretty experimental books. There's a new Doom Patrol, starring Casey Brinke, aka Space Case, whose life is turned upside down (it's already plenty weird) when she encounters Cliff Steele after he escapes a world within a gyro.

Also making a return is Shade (this time a "Changing Girl"), Cave Carson, and even Jack Kirby's Forager. While most of the Young Animal books have mostly inhabited their own world so far, that's all going to change when the Doom Patrol crosses over with the Justice League of America in early 2018. Until then, Batman's already making appearances in Mother Panic, the only Young Animal book currently featuring an original character.

12 THE WILD STORM RETURNS

wild-storm-header

Jim Lee and Brandon Choi founded WildStorm as one of the big studios in Image Comics in 1992 before selling it to DC Comics in 1998. While the WildStorm characters existed in their own universe, they were eventually integrated into the larger DCU in 2011 as part of the New 52. Suddenly, Midnighter, Apollo, Voodoo, Grifter, and the Stormwatch team were a part of the official continuity. Some characters even got their own books as part of DC's new 52-book lineup. That didn't last very long, though.

While Grifter and Stormwatch played roles in the New 52: Future's End weekly event and Midnighter enjoyed appearances in the Batman line, most of the WildStorm characters eventually disappeared. That is, until Warren Ellis was tapped to revive them in The Wild Storm #1 during the Rebirth relaunch.

11 BATMAN & DUKE

Duke Thomas

First introduced in Batman Vol. 2 #21 by Scott Snyder and Greg Capullo, Duke Thomas has been a part of Batman's life since the very beginning. The two first met during the "Zero Year" arc, the Dark Knight's revamped origin story in which Gotham is flooded by the Riddler and sent spiralling into chaos. Of course, a very green Batman saves the day in the end. This inspires Duke to follow in Batman's footsteps and be his own hero.

Duke isn't a Robin and not a traditional sidekick. Bruce is instead guiding Duke to figure out what kind of hero he wants to be. It's not so much Dynamic Duo as it is superhero academy. To top it all off, it's just been revealed that Duke -- now named The Signal -- is a meta-human and has a power that might lead Batman straight to the Dark Multiverse. More on that in a bit!

10 CONVERGENCE

DC Convergence Heroes From The Multiverse

Midway through the New 52 era, there were a lot of multiversal shenanigans afoot. Whether it was the weekly event New 52: Future's End or Earth 2: World's End or even Grant Morrison's Multiversity, which mapped out the 52 Earths of the DCU, there was a lot of work being done to organize the known multiverse. Why do you ask? Well, it was all leading to the big Convergence crossover event, which established that there were in fact an infinite amount of multiverses in DC's cosmology.

Suddenly, every version of a character who had ever appeared in a DC comic was fair game. The biggest thing to come out of this event was the return of pre-Flashpoint Superman. And he brought his wife Lois and son Jonathan along with him. While Convergence wasn't super well received, it was sort of the beginning of setting things right in the DCU.

9 HEROES IN LOVE

superman-lois-lane-header

Who says superheroes can't have a bit of romance in their lives? When the New 52 launched, it got rid of many of DC Comics' most famous married couples, such as Superman and Lois Lane, Aquaman and Mera, and Barry Allen and Iris West. Everyone was suddenly single and ready to mingle. A simple explanation for this is that when Dr. Manhattan stole ten years from the timeline, he made it so that these relationships hadn't yet bloomed.

But the lead up to the Rebirth relaunch began to change all of that. Clark and Lois from the old DCU had made it back to official continuity, along with a son named Jonathan (who we'll talk more about in a minute) and Aquaman proposed to Mera in the character's Rebirth special last year. Even Batman might get married to Catwoman! It looks like DC has a soft spot again.

8 THREE JOKERS

Three Jokers

Who is the Joker? That's a question the World's Greatest Detective has been unable to answer for 75 years. Sure, we've received several origin stories over the years, including the seminal The Killing Joke by Alan Moore and Brian Bolland as well as his most recent origin in "Zero Year" by Scott Snyder and Greg Capullo. Yet, those are all versions of a story that isn't entirely clear. Even the Joker likes to embellish when telling the story of who he was before becoming the Clown Prince of Crime.

Well, Geoff Johns and Jason Fabok made the Joker's origin story even more complicated in Justice League Vol. 2 #50 when it was revealed that there are in fact THREE Jokers running around. This would explain why the Joker is constantly able to cheat death and has changed so much throughout history, but it's still confusing as all hell.

7 CLAYFACE, SUPERHERO

Clayface in Detective Comics

If someone had told you five years ago that Clayface would one day become one of Batman's most important allies in Detective Comics, you probably would have laughed that person right out of the damn comic book shop. But that's exactly what's happened with the character in the hands of James Tynion IV. Clayface now works with Batman, Batwoman, Cassandra Cain, Batwing, Spoiler, Azrael, and more to protect Gotham from the threats that no single superhero can take on.

Seeing Basil Karlo's softer side is actually pretty heartwarming, and the villain turned hero even provides a bit of much needed comedy to the affair. If DC had a most improved award, this new, baby-faced Clayface would undoubtedly be a frontrunner. Some villains have hearts, too.

6 LEGACY

blue-beetle-bb-gun

One of the biggest changes during the New 52 timeline reboot was the end of the legacy structure -- the idea that the heroes of the Golden Age had passed down their mantles to successors who then passed them down to their sidekicks. Jay Garrick made way for Barry Allen who made way for Wally West. The Justice Society of America was the first superhero team, which was followed by the Justice League of America. The Teen Titans was a group made up of the sidekicks of members of the Justice League.

That was erased from continuity in the New 52's five-year timeline, which established the Justice League as the oldest group of heroes, banishing the JSA to Earth-2. Since the Rebirth relaunch, the JSA has been reintroduced and heroes like Jay Garrick, the original Flash, have returned.

5 JAY GARRICK RETURNS

Jay Garrick as The Flash in The Button

Comic book fans who know their history recognize Jay Garrick as the very first Flash. While he was a staple of DC Comics in the 1940s, he was eventually replaced in 1956 by Barry Allen, who remains the most lasting Flash in the company's history. Sure, Jay has continued to exist for the better part of a century, but never again in the starring role he enjoyed early on.

In fact, he's been missing for a bit since the New 52 relaunch, which established that Barry Allen was the very first Flash on our Earth, effectively erasing Jay from continuity. That is, until "The Button" crossover event, which revealed that Jay was trying to find his way back to our Earth through the Speed Force! We really hope he makes it back...

4 DICK GRAYSON, SECRET AGENT MAN

Dick Grayson Agent of Spyral

Dick Grayson has gone through many phases of his life, from being the first Robin the Boy Wonder to stepping out of the Dark Knight's shadow as Nightwing to leader of the Teen Titans. But no one ever expected him to become a secret agent for a secret spy organization. Yet that's exactly what happened in Grayson by Tom King, Tim Seeley, and Mikel Janin.

After Dick fakes his own death in the "Forever Evil" crossover event, Batman sends him on a secret assignment to infiltrate Spyral and find dirt on them. Suddenly, Dick was doing his best James Bond impression while still performing gravity-defying acrobatic stunts. Grayson also introduced quite a bit of sex appeal to the hero. This was around the time when people started worshipping his... assets.

3 NEW SUPERBOY

Jonathan Kent as Superboy

When the pre-Flashpoint Superman and Lois Lane were reintroduced to DC's New 52 continuity, they brought their son with them. Although Kon-El occupied the role of Superboy towards the end of the New 52, Superman's firstborn son was destined to become the new Superboy. We've been reading their father and son adventures ever since.

Interestingly enough, Jonathan Kent might be inspired by Jon Lane Kent, who was first introduced in 2013 as the son of Superman in an alternate future. His DNA was used to create a clone of Superboy in the present that was used for the first few years of the New 52. How little Jonathan Kent might fit into this possible future -- if at all -- is yet to be seen.

2 DARK MULTIVERSE

A dark version of Batman looking scary surrounded by an orange background in Dark Knights Metal.

Sometimes one multiverse just isn't enough, so Batman mastermind Scott Snyder is introducing the Dark Multiverse in 2017. If there are 52 Earths in the DC multiverse, then the this new, twisted multiverse is the dark matter in between that holds the entire cosmology together. It's not quite a nightmare universe full of evil versions of every superhero -- although the Justice League will face several evil versions of Batman in the Dark Nights: Metal event -- but it is a place where your fears can come to life, according to Snyder.

We find out in Dark Days: The Forge #1 that Batman's been investigating the mystery of Nth metal -- the element that gave Hawkman his powers -- since the beginning of Snyder and Greg Capullo's run, and it all leads him to this brand new setting in the DCU.

1 TWO FLASHES

Wally West as the Flash

Leading up to the release of DC Universe: Rebirth #1, there was a lot of speculation regarding whose mysterious arm was in the event book's Bible-inspired promo picture. Well, it was none other than Wally West, the forgotten successor and best friend of Barry Allen. In fact, most of the book is about Wally getting back to the DCU after floating for years in timelessness. It's only after Barry is able to remember Wally that the young hero is able to return.

But Wally didn't just continue in his role as Kid Flash after he returned. Barry decided to give him the title of Flash, which means that there are now two Flashes in the DCU. One fights with the Justice League and the other with the Titans. This isn't the first time there has been more than one Flash. This was also the case after Final Crisis, when it was Barry Allen who returned.

What other changes has DC made that shook the foundations of its universe? Help us complete our list in the comments!