It was an Avengers storyline, 1971’s “The Kree-Skrull War,” that essentially ended the Kree Empire’s desire to take over the Earth by revealing that the aliens actually wanted the planet as a staging ground for a long-running intergalactic war with another alien race called the Skrulls. The Avengers, as is their wont, got involved in the conflict and were instrumental in bringing it to an end, alongside the Inhumans — although, tellingly for future plot developments, it was the Kree leader known as “the Supreme Intelligence” that actually ended the war proper by accelerating the evolution of a regular teenage human to give him superpowers. That, it turns out, would end up proving to be an inspiration for future creators in both comics and, apparently, television.

(The Kree have subsequently found themselves in new intergalactic wars that inevitably draw in Earth’s superheroes. They’ve gone to war with the Skrulls again more than once, as well as the X-Men franchise’s Shi’ar Empire, Phalanx and many others. In fact, it’s safe to assume that the Kree are always out in space at war with one alien race or another.)

In later years, it would be revealed that the Kree were no strangers to human evolution. In fact, millions of years ago, the Kree had visited Earth and experimented on primitive humans, creating a subspecies of superpowered beings that would eventually be dubbed "Inhumans." The Inhumans, who were also more technologically advanced than the rest of humanity, would end up withdrawing from society by relocating to a hidden city on an island in the North Atlantic — something that might sound just a little familiar to anyone watching ABC’s Agents of SHIELD right now.

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In fact, Agents of SHIELD as a whole has had Kree at its heart this entire time, hidden in plain sight. That will change in the Dec. 2 episode, which will reveal that the mysterious blue alien whose blood resurrected Coulson and drove Garrett insane is, in fact, Kree. That same blood, it’s been revealed in recent episodes, also filled Coulson and Garrett’s minds with a map to a hidden city on an island in the North Atlantic — suggesting that the cinematic version of the Inhumans might appear onscreen long before the movie’s Nov. 2, 2018, release date.

(Of course, they might not: In comic book mythology, the Inhumans' base city Attilan has a history of moving about in order to avoid being discovered; it’s gone from the North Atlantic to the Andes, the Himalayas, and even the moon throughout the years. These days, it’s destroyed, with the remains lying in the Hudson Estuary in New York. Don’t be surprised if Coulson and his televisual team find the island, but only remains of the city that they’re actually looking for. After all, something has to be saved for the big screen.)

The background of that solitary Kree is something that will doubtlessly be explored in the ABC series; so far, all we know for sure is that his corpse was discovered by HYDRA during the Second World War and confiscated at the end of the war by the Strategic Scientific Reserve before ending up in the hands of SHIELD. That said, we also know that he shouldn’t have been on Earth; when Sif visited the series in its first season, she referenced the Kree but said, fairly definitively, that the race had never visited the planet. If one Kree had snuck onto Earth, who’s to say there weren’t others? Suddenly, Kyle MacLachlan’s character (and Skye, his daughter) suddenly look a little bit more … blue.

SHIELD’s dead alien isn’t the only Kree that we’ve seen onscreen. Ronan, the villain from this summer’s Guardians of the Galaxy, is also Kree, with developments since the film's August release making his melodramatic pronunciations about the fate of his race all the more important than they first appeared. According to Ronan, the cinematic Kree had been at war with Xandar, home planet of the Nova Corps, and has recently signed a peace treaty in order to avoid annihilation — a treaty that was not popular among the Kree, hence Ronan’s reign of terror as foiled by Star-Lord, Rocket et al.

Earlier, I mentioned Captain Marvel — or, to be exact, Captain Mar-Vell. Quite how he fits into the larger Marvel Studios plan remains to be seen, given the July 2018 date for a Captain Marvel movie, reportedly featuring the current incarnation of the character — a human woman called Carol Danvers whose DNA is rewritten to become half-Kree as the result of an accident involving Mar-Vell. We have yet to see Danvers (historically, an Air Force officer) in the cinematic universe, but surely it wouldn’t be too problematic to work her — and a Kree-related accident — into things given the increasing importance of Kree matters elsewhere. It’s an origin story waiting to happen.

The Kree, then, are an important step forward for Marvel’s onscreen plans — not only an in-story starting point for two of the four new concepts introduced in the Phase 3 movies (Sorry, Doctor Strange and Black Panther), but also a link between what happens on Marvel Earth and in Marvel Space. Perhaps, once everyone’s done with Avengers: Infinity War in 2019, we’ll see even more of them. Won’t we be due an alien invasion by then, anyway?

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