There have been a lot of huge events and important storylines in modern comic book history. Comic events, character deaths, new teams, allegiances, retcons and story arcs have shocked readers and changed the lives of superheroes forever. However, relatively few events can be said to have changed the course of comic book history. Now, at a time where comic books are possibly more popular than ever, we wanted to take a look back at some of the biggest and most important moments in the history of the medium.

These twelve events, whether they happened within story or in the “real” world, are ones that forever altered the future of comics. Some are smaller, yet momentous occasions. Others changed how stories were presented, or what could happen within the pages of a comic book. All of them were massive milestones for Marvel and DC, and together, tell a story about the history of the humble comic.

Here are 12 Moments That Changed Comic Book History.

12. The Release of Action Comics #1 (1938)

We couldn’t talk about major moments in comic book history without mentioning Action Comics #1. The first appearance of Superman is widely considered the most valuable comic book in existence, with a copy selling in 2014 for over $3 million. Action Comics #1 launched the Golden Age of Comics and kicked off the superhero storylines that we still love today.

Before Action Comics #1, comic book heroes (or pulp heroes – named after the cheap paper used to print the books) were usually adventurous detective and adventurer types (with a few Westerns thrown in for good measure). Protagonists solved mysteries and caught bad guys without superpowers or costumes, with names like Dick Tracy and Flash Gordon at the forefront. Action Comics changed all that, as readers could now enjoy new, superpowered stories.

11. Timely Publications and the Birth of Marvel (1939)

DC published its first book in 1935, although the groundbreaking Action Comics #1 didn’t debut until 1938. Marvel, meanwhile, didn’t get started until 1939. Beginning as Timely Publications, the company still carried the Marvel name with its first issue titled Marvel Comics #1, featuring the Human Torch and Namor, The Sub-Mariner, on the cover. Timely became known as Atlas in the '50s (publishing more horror, crime and westerns), before becoming Marvel in 1961, when the company launched their flagship team, The Fantastic Four.

Inspired by the popularity of DC’s Justice League of America, Marvel wanted to put a superhero team front and center for their company. Stan Lee, now one of the most famous names in comics, was a writer for Marvel who wanted to create characters that could appeal to all ages, not just children. Along with Jack Kirby, Lee and Marvel created the Fantastic Four, a completely different kind of superhero team; the group had no secret identities, a hero looked like a monster, and the team dealt with politics and personal issues. Marvel, and superheroes, would never be the same.

10. The Publication Of ‘Seduction of the Innocent’ (1954)

In 1954, psychiatrist Fredric Wertham published a book that would affect the comic industry in a major way. Seduction of the Innocent didn’t just criticize comics for not being educational; it claimed that reading comics caused children to become juvenile delinquents. Among the allegations he levelled at Superman & Co. were that they promoted homosexuality, violence, crime, and taught children to ignore the laws of physics. Batman & Robin were accused of homosexual undertones, Superman was labelled an un-American fascist, and Wonder Woman a bondage-loving lesbian.

The book received widespread attention, and had a major effect on comic sales – understandably. Parents didn’t want their children growing up to be violent, deviant criminals. After his findings were discussed by the Senate Subcommittee on Juvenile Delinquency, comic publishers needed to take action to reassure parents that their comics were safe to read. The Comics Code Authority was created to sanitize comics, removing violence, horror, and making sure that bad guys were always punished. Comics that adhered to these rules got the CCA stamp of approval. However, the code became more and more relaxed as years went by, before being abandoned entirely in the early 2000s.

9. The Appearance of Black Panther and Falcon (1966, 1969)

Comic books aren’t the most diverse fictional worlds – largely due to the age of the characters and the standards of the '40s and '50s, superheroes were originally pretty much all white, American (or Kryptonian!) and straight. However, superheroes of color may have been around longer than you think.

Black Panther (T’Challa) was the first black modern superhero, making his debut in 1966 when the Fantastic Four went on a mission to Wakanda. Marvel’s flagship team were invited there by Black Panther, who battled them to test their strength before asking for their help. Falcon (Sam Wilson) appeared a few years later in 1969 in a Captain America comic, where Sam Wilson uses a trained falcon to help Captain America escape the Exiles. These two are accepted as the first black Marvel characters (the first black African and American, respectively), paving the way for characters such as Storm, Luke Cage, and others.

DC was a lot slower to bring a bit of diversity into their comics – the first black DC superhero was Green Lantern John Stewart, who made his debut in 1971.

8. The Death of Gwen Stacy (1973)

One of the most shocking deaths in comic book history occurred in 1973, when Spider-Man’s ongoing rivalry with the Green Goblin involved the adorable blonde, Gwen Stacy. Gwen, Peter Parker’s girlfriend at the time, was kidnapped by Norman Osborn's alter-ego in a classic attack-the-loved-ones gambit. Goblin threw her off a bridge, and Spidey almost saved her…but as his webbing caught her leg and prevented her from plummeting to her death, the sudden stop snapped her neck, killing her instantly.

Comic book deaths have become almost expected at this point, but in the early ‘70s, this was a true shocker; the hero always saved the girl in the end. The Death of Gwen Stacy was the first time that we really saw a superhero fail to save the woman he loved, and the fact that it was his attempt at saving her that did her in made the comic all the more heartbreaking. This marked the beginning of the Bronze Age in comics, a time where wives and girlfriends started to meet less-than-pleasant ends. This new tendency for loved ones to meet a sticky end was even nicknamed "Gwen Stacy Syndrome."

7. The Appearance of Northstar (1979)

In 1979, the X-Men were flying home from Japan when they are forced to make an emergency landing in Canada, where they meet (and battle) a Canadian superhero team known as Alpha Flight for the first time. A relatively minor team, Alpha Flight introduced one incredibly important character: Northstar, the very first openly gay superhero.

When the skiing speedster was first introduced, creators Chris Claremont and John Byrne weren’t able to do much more than hint about his sexuality. However, by 1992, Northstar came out publicly in the comics, as part of a storyline about HIV awareness. The character even wrote a book about being both mutant and gay, entitled Born Normal. Only a few years ago, in 2012, Northstar made headlines again when he married his boyfriend Kyle in the first gay wedding featured in mainstream comics. Now, of course, there are far more LGBT superheroes, but Northstar was the first to pave the way.

6. Crisis on Infinite Earths (1985-1986)

By the mid '80s, many of DC’s superheroes had been around for around fifty years, and things were starting to get a little bit complicated. Early versions of characters didn’t match up to later versions, and the comics were rife with continuity problems. Ages, time periods, powers – there were little flaws in continuity everywhere, especially with the bigger characters. While most fans were willing to overlook these flaws, it was becoming more and more problematic with each passing year.

Crisis on Infinite Earths essentially wiped out these continuity issues, the multiverse, and several characters, giving us a streamlined and consistent DC universe fo the first time in decades. The storyline itself brought together heroes from all over DC’s universes to battle the Anti-Monitor, and ended with several major deaths (neither Supergirl nor Barry Allen survive, sorry television crossover fans). As well as resetting the DC universe and revitalizing characters and storylines, Crisis was one of the first major, overarching comic book crossover events.

5. The Dark Knight Returns Ushers In A New Age (1986)

You’ll often hear periods of comic book history referred to as “ages." The Golden Age, The Silver Age, The Bronze Age, etc. Our current age is often called The Dark Age of Comics (though it's also been referred to as the Iron Age and The Modern Age), and it began with the release of Frank Miller’s The Dark Knight Returns in 1986.

Miller’s story about a much older Batman in a dystopian Gotham was a total break from most of his earlier incarnations (especially the campy Adam West TV Batman of the ‘60s and ‘70s). The bright colors and lighter tone were gone, replaced with a decidedly more adult story. The Dark Knight Returns wasn’t just darker and grittier than the classic comic fare, it was also marketed toward adults, rather than children. This marked a huge change for the comic industry, as graphic novels began to feature more sex, violence and psychologically damaged characters. Alan Moore’s Watchmen, which also debuted in 1986, is also often named in a discussion of this massive shift in comics, one that paved the way for characters like the hugely popular Deadpool and the kind of adult-oriented storylines that we enjoy today.

4. The Death of Superman (1992)

In 1993, DC’s flagship hero, Superman, took on yet another seemingly unstoppable bad guy. This time, it was the monstrous creature known as Doomsday, and the fight didn’t end the way that most expected it to. While Superman did of course take down the bad guy, both Doomsday and Superman succumbed to their injuries at the end of the fight. While some superheroes have been resurrected multiple times, this was the first and only time that Clark Kent bit the dust, and it sent shockwaves through the world of comics.

Although this was not the first time that a major superhero died at the end of a story arc (that would be Jean Grey in the Dark Phoenix Saga, although she was resurrected relatively quickly), this was Superman, and it was the first truly major death (and subsequent resurrection) for DC. Following Superman’s return, a slew of other long-dead characters were resurrected, including Jason Todd and Bucky Barnes. These were characters whose deaths had major impacts on Batman and Captain America, respectively, and so were presumed to be permanently dead. The Death and Return of Superman changed the rules for DC, opening the door for anyone to come back to life.

3. Marvel’s Financial Difficulties (1996)

It may be hard to believe now that Marvel is a household name, but in the mid-90s, the comic giant was in dire financial straits. By the late ‘80s, comics (and comic collecting) had become hugely popular. Vintage books were being sold for vast sums of money, and more and more people were starting to collect comics as an investment. At the same time, Marvel was purchased by Ron Perelman, who made a series of less-than-brilliant financial decisions, spending a reported $700 million on toy and trading card companies, and raising the price of comics. Sadly, the plan didn’t work. The comics bubble burst, and fans stopped purchasing comics altogether, or at least, purchased far fewer. Sales fell by 70%. Marvel was in trouble.

The company filed for bankruptcy in 1996 to pay off their debts, and attempted to recoup losses with several different schemes. Most of these failed (such as new trading cards and themed restaurants), but one succeeded: Marvel sold the film rights to several of their biggest characters to various studios. Blade found some success, paving the way for X-Men in 2000 and Spider-Man in 2002. Between these three films, the superhero renaissance was launched, catapulting Marvel back to success on the big screen (and into rights-sharing issues that continue to this day). Without their financial troubles, however, the MCU as we know it may never have come into being.

2. Marvel & DC's Amalgam Universe (1996-1997)

Marvel and DC are the two biggest players in comic books, especially when considering the current superhero movie renaissance. They are definitely each other’s competition, and are often described as being at war with each other – even though it’s usually the fans who are making the most noise about DC vs. Marvel. The two have produced crossovers in the past — where a DC and a Marvel character would face off — but that was nothing compared to what happened in the ‘90s, when the two giants came together to merge characters in a totally new universe.

Amalgam Comics is an imprint created by Marvel and DC which produced twenty-four issues, each combining a Marvel and a DC hero. New characters included Iron Lantern (Iron Man and Green Lantern), Dark Claw (Batman and Wolverine), and Lobo The Duck (Lobo and Howard the Duck). The series was created with a full backstory and an entirely new universe, created after a DC vs. Marvel series, which pitted hero against hero. While the stories themselves were never intended to be taken too seriously, this was a comic event that proves that Marvel and DC can actually get along and have a lot of fun together – something that the more rabid fans of one or the other should really keep in mind.

1. Flashpoint/ The New 52 (2011)

In 2011, 26 years after Crisis on Infinite Earths re-set the DC continuity, DC decided to re-launch many of its titles and characters for a second time. The relaunch involved major change across the board – not just within the stories themselves, but in the number of titles released every month, the publication of hard copy and digital comics, and the inclusion of some characters from DC imprints.

The New 52 started with the Flashpoint storyline, where Barry Allen wakes up in an alternate reality in which only he is aware that the world has changed. In a complicated Flash-centric storyline, it is revealed that Barry’s time-travelling is what has changed the world that he knew, forcing him to go back in time again and set things right. Flashpoint combined and re-set several different timelines (including that of imprints Vertigo and WildStorm), after which DC launched their New 52.

The first complete reboot of an entire comic world, the events of Flashpoint and the New 52 made it much easier for new readers to enter the world of DC. They could simply pick one of the 52 new titles, and read from issue 1, rather than having to go back to the post-crisis world from the '80s or even the earliest comics of the '30s. Marvel subsequently attempted a reboot, entitled Marvel Now, in 2012. Their re-launch wasn't quite as successful as the New 52, however, and Marvel has created a second reboot (All New, All Different Marvel) which rebranded several titles in 2015. Neither of these has been as far-reaching as the New 52. Additionally, DC has a major event, entitled Rebirth, going on at this very moment, though they've clearly stated that it's very much "not a reboot." We're just not sure we believe them.

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Which moment in comic book history stands out the most to you? Did we miss any of your favorites? Be sure to let us know in the comments below!