In Captain Marvel, Carol Danvers and her various Earth allies are dealing with a threat from two sides: the Skrulls and the Kree. But while the Kree have shown up in the Marvel Cinematic Universe sporadically over the years, this marks the first ever appearance of the Skrulls.
The Kree-Skrull War is finally happening in the MCU, after being so briefly mentioned in 2014’s Guardians of the Galaxy, and here’s what you need to know about how that all went down in the comics.
The Kree and the Skrulls are two different alien races in the Marvel universe, both created by Stan Lee and Jack Kirby. Each had their first appearance in a Fantastic Four comic; the Skrulls in 1962’s Fantastic Four #2 and the Kree 1967’s Fantastic Four #65.
Originally, the Skrulls were a race who were willing to share their technology with other aliens, and used their powers of shapeshifting to ease relations whenever they encountered a new race. Eventually, they visited the Kree homeworld of Hala, where the Kree murdered the Skrull delegates and stole their technology. Only decades later, the Kree’s reverse engineered discoveries had made them the Skrulls’ technological equal.
As a result, Skrull culture was forced to become as vicious as their enemies, leading to a nearly endless war. Both species made strides to gain an edge over the other: The Skrulls created the very first Cosmic Cube (it didn’t go well), and the Kree created the Supreme Intelligence, a cyberogranic supercomputer that made all their decisions for them (this also didn’t go well, eventually).
But everything truly changed when the Kree-Skrull War reached the planet Earth.
It was the Kree who first discovered the human race, thousands of years before modern times. They began to experiment on various species, including Homo sapiens, both to craft them into a source of foot soldiers and to figure out how to avoid their own evolutionary stagnation. The experiments led to the creation of the superpowered Inhumans, but the Supreme Intelligence ordered all such experiments destroyed after foreseeing the Kree would eventually be destroyed by their own creations. The Inhumans escaped the Kree slaughter and went on to form various hidden societies across Earth; the only one that really matters is the Royal Family of Atillan, but we’ll get to them later on.
Skrulls became aware of the Earth much later than the Kree, deciding it was worth conquering after stumbling upon it in the 1950s. Various scouts have been sent down to infiltrate Earth — which is pretty easily done when you can shapeshift into anyone. But neither side realized that the planet has a lot of superheroes until it was too late.
Those realizations came a the hands of the Fantastic Four. The Four took down the Kree’s military head Ronan the Accuser, when he came to Earth looking to kill the Inhuman Royal Family. In another incident, Mr. Fantastic hypnotized Skrull infiltrators into shapeshift into, and forever believing, that they were simple cows.
Once it turned out that the Earth had superpowered people of its own, the planet became of greater importance to the Kree and Skrulls. Earth’s heroes didn’t intentionally pick a side, but still wound up favoring the Kree, sort of. A Kree soldier named Mar-vell, who originally infiltrated Earth to determine if it would be a threat to his people, became one of its many protectors while in hiding, even joining the ranks of the Avengers.
While working on Earth as the hero Captain Marvel, Mar-vell made contact with two important characters: The first was Rick Jones, a former sidekick of the Hulk’s who frequently swapped places with Mar-vell in the Negative Zone for a few hours. The second was Air Force officer Carol Danvers, the future Ms. (and later Captain) Marvel.
Mar-vell’s presence on Earth eventually lead to the Kree-Skrull War playing out in grand, ridiculous fashion in an eponymous comic book event. The story included Ant-Man being morphed into a caveman and the Vision being attacked by the Skrull cows. Captured and taken to the Skrull Empire, Mar-vell, with the help of the Supreme Intelligence and his friend Rick Jones’ new power of the Destiny Force — an energy source where you realize your self worth, basically — brought the war to a halt. A mob killed the skrull posing as the xenophobic senator who incited the conflict in the first place, and Marvel’s Illuminati tell both the Kree and the Skrulls to back off of Earth. This is normally where things end happily ever after, but that didn’t happen in the slightest, and things actually got much worse.
After the end of the original Kree-Skrull War, neither race were able to leave the cycle of conflict. The two races skirmished in the chaos of Thanos’ decimation of half the universe, which only led to the respective empires to decline even further after the universe was restored. The Kree got into a war with the Shi’ar, leading to the devastation of their empire and eventual surrender, at which point Ronan killed the Supreme Intelligence and assumed control of the Kree. But not for long, after Ultron isolated Kree space from the rest of the universe.
If the Kree were in a bad way, then the Skrulls got the even more raw end of the deal. For a while, they lost their ability to shapeshift. Not long after that, Galactus destroyed their Throneworld — billions of lives and the Skrull royal family were lost. Only a few hundred factions of Skrulls remained, and those fell into a civil war, bickering over how best to regain the foothold they once had. Then Annihilus and his Annihilation Wave made the Skrull Empire one of their first targets. The war had ended, essentially, because both empires were so bad off.
And then came the Secret Invasion.
For the early to mid-2000s, it seemed like the Skrulls were on their last legs, but that would change. After Galactus’ attack, a new Skrull queen named Veranke took the throne. Like the rest of her kind, she believed that the Earth was religiously and rightfully theirs to own. So, thanks to previous observations the Skrulls had made of Earth’s heroes, she came up with the perfect way to take over Earth: Conquer the planet from within using their mightiest heroes.
Veranke was on the front lines of the infiltration in the form of Spider-Woman, posing as a member of the New Avengers throughout their inception and the superhero Civil War. Using shapeshifted agents hiding in SHIELD, the Skrulls destabilized the superhero community and sowed distrust, nearly defeating all of them and taking over Earth. Once again, however, they found themselves defeated thanks to the brilliance of Reed Richards, who constructed a device that could detect the shapeshifters. You can guess the story from there: The Skrulls are defeated, Veranke is killed by Norman Osborn, the heroes who were impersonated are rescued. SHIELD was dissolved by the President due to the numerous infiltrators that were in their ranks.
More or less. Secret Invasion left the Skrulls in even smaller numbers than before, and those that remain are either actively trying to regain power on the Skrull homeworld or just trying to survive in Earth or the galaxy at large. Right now, the Skrull Emperor is none other than Kl’rt, the very first Super-Skrull, a skrull genetically engineered to have all the powers of the Fantastic Four. If you want to see what some Skrulls are up to, there’s an upcoming miniseries that will shed light on that.
And the Kree aren’t faring much better, what with Hala being destroyed in 2015’s Black Vortex storyline. Their biggest problem, though, has been dealing with something of a civil war of their own with the Inhumans. The Royal Family very briefly ruled over the Kree, but that didn’t last terribly long. More recently, a contingency of Kree sent away by the Supreme Intelligence generations ago have since returned to Kree space, killed Ronan, and decided to clean house by rebuilding Hala and their empire.
To that end, they made a Super-Inhuman called Vox to kill all Inhumans, and forcibly experimented on the survivors. With that, the prophecy the Kree feared finally came to pass: The king of the Inhumans, Black Bolt, killed the remaining Kree to avenge his people, effectively bringing about the end of the empire.
Even if you take away Carol’s involvement in the war between the two races, her connection to the Kree is deeper than originally thought. The recent miniseries The Life of Captain Marvel, by Margaret Stohl, Carlos Pacheco, and Marcio Menyz, revealed that Carol has been a Kree-Human hybrid since the day she was born.
Her mother Marie is actually a Kree Captain named Mari-Ell, who landed on Earth decades ago and went into hiding with Joe Danvers. Later on, the two had Carol — her Kree name being Car-Ell, which means “Champion.” Instead of gaining her powers from having her DNA mixed with Mar-vell’s during an explosion, as we’d thought for many years, that explosion ended up jumpstarting her innate Kree abilities. Carol learned all of this when a Kree Kleaner (not a typo) finally came hunting for Marie, to punish her for deserting. The Danvers women briefly used their cosmic powers side by side to defeat the Kleaner.
Right now, Carol being part Kree all along seems to be the one tangible connection that can be made between the comics version of Carol and the one to be played by Brie Larson. Not all of this will make it into Captain Marvel proper, but when the film says that the war has been going on for a long time, they aren’t kidding. Comics are eternal, and it seems likely that at some point, the spark of war will ignite between these two powerful races again.