Kree and Skrulls: The Kree-Skrull War, Shapeshifting and Secret Invasion Explained

The Skrulls came first, as a joke. Fantastic Four #2 (January 1962), by Stan Lee and Jack Kirby, has four shapeshifting aliens impersonate the team to discredit it; Reed Richards tricks them by showing them panels from a monster comic as proof of Earth's defences, and hypnotizes the survivors into believing they are cows. From that start the Skrulls grew into an empire: green-skinned, pointed-eared, chin-ridged humanoids from the planet Skrullos in the Drox system of the Andromeda galaxy, with a throneworld, Tarnax IV, that the planet-eater Galactus consumed in 1983, and a culture built on infiltration, since a species that can look like anything will conquer by replacement rather than by force.

The Kree arrived five years later as the Skrulls' opposite. Fantastic Four #65 (August 1967) introduced Ronan the Accuser and, behind him, an empire from the planet Hala in the Large Magellanic Cloud, ruled by the Supreme Intelligence, a green face in a tank made of the preserved minds of the species' greatest dead. The Kree come in two strains, the blue-skinned original stock and a pink-skinned majority that resembles humans, and their culture is military, hierarchical and fixed on a genetic dead end: the species stopped evolving long ago and has spent millennia trying to engineer its way out, which is why it experimented on early humans and produced the Inhumans. Captain Mar-Vell, the Kree officer who defected to Earth in 1967, is the empire's conscience and the source of the name Carol Danvers later took.

The war that defines both species was a nine-issue Avengers story. Roy Thomas and Neal Adams' "Kree-Skrull War," in Avengers #89 to #97 from 1971 to 1972, has the two empires' ancient conflict spill onto Earth, with the Skrulls kidnapping the Avengers' allies, the Kree Supreme Intelligence manipulating events to awaken a latent human potential, a Skrull impersonating a senator to launch an anti-alien crusade, and a cattle-shaped Skrull from 1962 turning up on a Midwestern farm. It ends with the human Rick Jones, his mind unlocked by the Supreme Intelligence, freezing both fleets, and with the war returned to a stalemate it has kept since.

The backstory the story established has held. The Kree and Skrulls met a million years ago on the planet of the Cotati, a plant species; the Skrulls, then peaceful traders, held a contest between the Kree and the Cotati to decide which would receive their technology, the Cotati won, and the Kree murdered both the Cotati and the Skrull delegation and took the technology anyway. Every Kree-Skrull conflict since is that first betrayal replayed, and the Skrulls' turn from traders to infiltrators is the comics' account of what losing does to a people.

A Skrull can be anyone, which makes the species the comics' standing device for paranoia. Skrull shapeshifting copies a form completely, including clothing and, in later stories, powers, and the Super-Skrull, introduced in 1963, carries all four of the Fantastic Four's abilities at once. Secret Invasion (2008), by Brian Michael Bendis, took the device to its end: a religious faction of Skrulls, believing Earth promised to them by prophecy, had spent years replacing heroes, including Spider-Woman and Hank Pym, and the story's question, "who do you trust," ran through every Marvel title for a year. The invasion was defeated; the replaced heroes came home to lives someone else had lived.

The films reversed the polarity. Captain Marvel (2019) opens on the Kree side, with Carol Danvers a Kree soldier fighting Skrull "terrorists," and turns halfway: the Skrulls, led by Ben Mendelsohn's Talos, are refugees whose worlds the Kree destroyed, and the empire Carol served is the aggressor. The Secret Invasion series (2023) then gave the refugees a radical wing that had infiltrated governments for thirty years, so that the films ended up with both readings, the Skrull as victim and the Skrull as impostor, which is roughly where the comics have been since 1971.

The Skrulls are the Reptilian conspiracy with a publication date. David Icke's The Biggest Secret (1999) claims that a species of shapeshifting reptiles occupies the bodies and offices of the world's rulers, holding their human form by an act of will and lapsing into scales when tired; the Reptilian aliens article traces the claim and its sources, and the conspiracy theories ranked article explains why its habit of naming Jewish families makes it an antisemitic trope in a new skin. The Skrull impersonating a senator to whip up a crusade against aliens appeared in Avengers #93 in 1971, twenty-eight years earlier, and the impostor-in-office is the plot of Secret Invasion in both media. Marvel did not invent the fear; it published it with a green face on it in time for the theory's authors to grow up reading it.

The Kree, meanwhile, are the hybrid program in comic form. A superior species visits Earth in prehistory, alters the human line to make a more useful strain, and leaves the results to be discovered later: that is the Inhumans' origin and it is the story that the abduction researchers of the 1980s told about the Greys, with Terrigen crystals in place of an examination table. The two Marvel empires between them cover the lore's two great fears, the alien who replaces us and the alien who improves us, and the comics have been putting them in the same room since Rick Jones froze the fleets.