There are several ways for the MCU Skrulls to be identified, even when they're masquerading as someone else. Marvel Studios introduced the Skrulls to the MCU in 2019's Captain Marvel, which saw the shape-shifting race seeking refuge after being forced into a lengthy war with the Kree. In a major change from their Marvel Comics history, the MCU's Skrulls were shown as allies to humanity, an otherwise-peaceful race who had forged themselves into warriors to survive. Even so, Phase 5's Secret Invasion has proven how dangerous Skrulls can be, as a rebellious faction has been quietly infiltrating Earth for a number of years, assuming the identities of high-ranking MCU figures.
Skrulls made their debut in Marvel Comics in 1962, and have regularly been shown to be formidable warriors, but always as foes to Earth's Mightiest Heroes. Marvel Comics' Secret Invasion event marked their biggest storyline yet, as the Skrulls embarked on a full-scale invasion of Earth, with many of Marvel's heroes being replaced. While their backstory has been changed for the MCU, Marvel Studios' Skrulls still demonstrate the ability to shape-shift, which allows them to integrate into life among humans. However, this is also a terrifying concept, as anyone in the MCU could feasibly be a Skrull, though there are several ways that Skrulls can be identified, even when disguised.
6 Skrulls Don’t Take On The Characteristics Of Those They Mimic
In their natural forms, Skrulls are instantly recognizable thanks to their green skin, pointed-back ears, and lack of body hair. However, their innate shape-shifting ability allows them to assume the form of any living being down to the DNA, which enables them to blend in seamlessly in any civilization. This has been seen multiple times in their short career in the MCU, as Skrulls have been shown to impersonate the likes of Soh-Larr, Carol Danvers, R. Keller, Phil Coulson, Maria Hill, and Nick Fury in Secret Invasion. Even so, the Skrulls' impersonation is never an exact match, even though the voice, physical body, and clothing can all be mimicked precisely.
While Skrulls can transform themselves into an exact match of whomever they're impersonating, they can't take on the personality of their copied body. This means that it should be fairly straightforward to decipher who is a Skrull, as slight mannerisms would be harder to emulate. This is because a person's personality is not a matter of their DNA. Skrulls can copy personality to a point, as they can extract memories that would allow them to mimic speech patterns and physical routines. In theory, the fact that the more personal characteristics can't be copied by Skrulls should make it easy to identify them, but this isn't always the case.
5 Skrulls Only Copy Short-Term Memories
When transforming into the shape of another living being, the Skrulls are able to replicate the recent memories of their copied body, which allows them to better integrate into society. The Skrulls have also been shown to see memories further back in a person's life, though they need to use advanced technology to extract these memories, as seen in the case of Carol Danvers in Captain Marvel and several human hosts in Secret Invasion. The fact that Skrulls can only copy the short-term memories of the individual they're impersonating means there is one sure-fire way to identify whether someone is a Skrull: simply to question them.
During Captain Marvel, Danvers questions Nick Fury about his early life to prove he's not a Skrull, and Yon-Rogg questions a Skrull disguised as Captain Marvel - who fails the test. This appears to be a foolproof technique to identify a Skrull, and one popularly used among the Kree forces themselves. It seems as though the Skrulls may have improved their system for replacing humans, however, as Secret Invasion revealed that machines are being used to extract deeper memories from host bodies, perhaps allowing the Skrull rebellion to easier infiltrate humanity, spreading out even further in preparation for their impending attack.
4 Skrulls Can’t Mimic Superhuman Gifts
As well as being unable to mimic personality traits and distant memories, the Skrulls are also unable to copy superhuman gifts, should they assume the form of a superhero or enhanced person. This would surely make it easy to determine who would be a Skrull if some of the MCU's most notable heroes find themselves being replaced, as many of Earth's Mightiest Heroes have very specific supernatural or superhuman powers that make them instantly recognizable. While the Skrulls may not be able to copy pre-existing superpowers, it seems possible that Skrulls could be granted enhanced abilities of their own, as seen in the trailers for Secret Invasion.
Kingsley Ben-Adir debuted as Gravik in Secret Invasion episode 1, "Resurrection," the leader of the Skrull rebellion on Earth. Although not much is yet known about the sinister new Skrull, trailers for Secret Invasion revealed that he will find himself being enhanced during the series, which has led many to believe he could be assuming the role of Marvel Comics' Super-Skrull. The Super-Skrull was gifted the abilities of the Fantastic Four, granting him superior power to his fellow Skrulls, and this appears to be the case for Gravik in the MCU's Phase 5. This could perhaps make it more difficult to identify a Skrull if they're masquerading as a superhero.
3 Skrulls Have Innate Enhanced Abilities
While Skrulls may not be able to copy superhuman abilities, they do have an impressive set of innate powers gifted to them from their Skrull physiology. As well as being able to shape-shift into the form of any living being, Skrulls also possess a wide variety of augmented powers thanks to their bodies not being carbon-based like humans. Throughout their appearances in Captain Marvel and Secret Invasion, Skrulls have proven themselves to be incredibly strong, and during intense fight scenes, have been shown to be durable and agile combatants. These gifts would certainly make them stand out among the average human.
Skrulls also have a much longer lifespan than humans, which would be a clear giveaway should a Skrull be masquerading as a human for several decades - as in the case of Ben Mendelsohn's Talos, who has barely changed in thirty years. Secret Invasion also confirmed that Skrulls have an immunity to high levels of radiation. This makes an abandoned nuclear facility the perfect location for Gravik to set up his base, as the Skrulls aren't affected by radiation. This also spells bad news for humanity, as Gravik intends to eradicate the human race using nuclear radiation, which is harmless to Skrulls, and certainly sets them apart from any regular human.
2 Skrulls Revert To Their Natural Form When They’re Killed
This is perhaps the most drastic way to determine whether someone is a Skrull, but killing them certainly works, as Skrulls revert to their natural, green-skinned form when they die. Unfortunately, if someone is suspected to be a Skrull and is killed, but turns out to actually be human, there could be dire consequences of this action. Even so, this method is a surefire way to identify a Skrull, as their shape-shifting transformation can't be held up once they've ed away. This has been seen several times in the MCU, such as with a Skrull disguised as Phil Coulson in Captain Marvel, and more recently in Secret Invasion episode 1.
Secret Invasion's premiere episode opened with Martin Freeman's Everett K. Ross listening to CIA Agent Prescod detail the Skrull rebellion's plan of world domination, before revealing himself to be a Skrull. Ross was eventually killed by Talos, transforming back into a Skrull in front of Maria Hill, acting as the first piece of evidence she needed to determine the Skrulls were setting their plan into motion, and Nick Fury needed to return to Earth. This reveal was shocking, as Ross had been a staple of the Black Panther franchise after his debut in 2016's Captain America: Civil War, though it's now unclear exactly how long he's been a Skrull in disguise.
1 Skrulls Can Be Detected In The MCU
Skrull Detectors haven't yet been seen in the live-action MCU, but they have been confirmed to exist thanks to the Guardians of the Galaxy Prequel Infinite Comic and the Captain Marvel prequel novel, Captain Marvel: Starforce on the Rise. Skrull Detectors can trace a unique piece of code in a Skrull's DNA, determining whether that person is a Skrull or not. These Detectors were used by Kree warriors during the Kree-Skrull War, and were later being sold by a black market dealer on a planet named Conjunction, which Gamora visited. Though they haven't yet made it into live-action, Skrull Detectors could be key to Secret Invasion's storyline.
Skrull Detectors also play a major role in Marvel Comics' Secret Invasion storyline, and subsequent storylines, with Tony Stark's Iron Man even having a Detector fitted into his Iron Man suit, allowing him to see through Skrull illusions. This would be a very handy piece of tech in the MCU's Phase 5, particularly if some more notable MCU characters are revealed as Skrulls in disguise. It's also possible that heroes with telepathic abilities, psychics, and magic s in the Marvel Cinematic Universe could easily be able to identify who is a Skrull, meaning it may not be so simple for Skrulls to blend into humanity as they might have initially expected.
