Unmarked spoilers follow!
The Skrull Empire was once a peaceful and scholarly civilization which ruled over a large sector of space. However, first contact with the Kree barbarians of the planet Hala led to a violent rivalry between the two races. Even as the Kree adopted the Skrulls' higher level of technology in order to compete with them, the Skrulls learned to become aggressive, hateful, and chauvinistic from the pressures of perpetual warfare with the Kree menace. The last straw for the Skrulls was the destruction of their homeworld Skrullos by Galactus, which reduced them to a semi-nomadic existence. Motivated by their state-sanctioned superstitions of a divine exodus that will lead them to a new homeworld on Earth, the Skrull Empire desires to make that planet their own, even while embroiled in the power struggle with the Kree for that corner of the galaxy. In spite of their insidious plans, which involve infiltration of human society at all levels by Skrull impostors, the Skrulls are the more benevolent counterpart to the Kree, who have far less of an excuse for wanting to conquer the Earth and are also far quicker to resort to the methodology of subjugation through absolute genocide.
- Aliens Are Bastards: Played with; they serve as villains and do commit villainous acts, but they don't appear very malicious and were willing to spare humans (as slaves but still). In fact, if you take into account the fact they were only trying to get a new home, they appear almost sympathetic in comparison to the Kree Empire.
- Alien Invasion: What the Skrulls are doing here.
- Catchphrase: "As it is written" (a reference to the Prophecy that says Earth would be their new homeworld).
- The fact that it replaces the comics' "He loves you" may be a Jesus Taboo of sorts, since said "He" is the God worshipped by the Skrulls.
- Cowboy Be Bop At His Computer: Marvel's announcement of the winners of polls for best Avenger, villain, etc., claims that the Skrulls wanted to destroy humanity, instead of enslave it.
- Egocentrically Religious: Their religion holds that in the aftermath of Skrullos's destruction the Empire is destined to find a new homeworld in the form of the Earth. Naturally, these beliefs only place significance on the Skrulls' exodus and the Earth as the Skrulls' holy land, and they could hardly say any less about the role in the grand scheme that the Earth's human inhabitants have to play. Ergo, the humans can be tolerated to a degree, but to the Skrulls they are an extraneous consideration.
- Even Evil Has Standards: Downplayed. When Madam Viper and Captain America interrogate a Skrull, he tells them of their plan to take over Earth via very meticulously planned subterfuge and infiltration. When Viper accuses them of wishing to slaughter the human race, the Skrull insists that they don't want to render the human race extinct and those who willingly surrender will be spared. However, it crosses over into Pragmatic Villainy as they'll be kept as slaves if they do (and there's nothing to suggest the Skrulls will let anyone get their freedom back).
- FaceHeel Turn: As a race and an empire, their turn to darkness was when their accidental endowment of the belligerent Kree with the wonders of their technology created a militant rival that they had to match in ferocity and ruthlessness just to compete with.
- Fantastic Racism: Not as bad as the Kree, but it says something that the Skrulls decided Earth couldn't be their new home without first dispossessing the natives of their rights, land, and dignity. And let's not forget that while it's not what they would have wanted to do, the Skrull Empire's contingency in the event that the human population couldn't be controlled was to exterminate it with the A.I.M. satellite grid they co-opted.
- Green and Mean: Their default form has green skin.
- Invading Refugees: They try to claim Earth as their new homeworld after Galactus destroys their original home.
- Not-So-Well-Intentioned Extremist: The Skrulls try to get Earth to submit by using their Captain America impersonator to convince the world's populace that subjugation to the Skrull Empire will ultimately benefit the whole planet. While it remains to be seen whether the Skrulls would have ruled over humanity semi-benevolently as they claimed, it nevertheless also holds true that the Skrulls took over Earth entirely for their own benefit, not humankind's, and also that the Skrulls were prepared to cause mass genocide of the human race in the eventuality of overwhelming human resistance.
- Paranoia Fuel: This is an Invoked tactic that they use In-Universe.
- Pointy Ears: In their natural form.
- Reptilian Conspiracy: They're green-skinned, reptilian, shapeshifting aliens who infiltrate and manipulate societies by replacing key leaders and figures of power.
- Something Only They Would Say: They're a unique and clever subversion, even in the comics. The Skrulls were smart enough to understand that appearance alone is not enough to fool everyone into thinking they are who they say they are, so they developed technology to absorb the memories and personalities of those they take the form of, meaning this tactic wouldn't work as they know basically everything about them.
- Voluntary Shapeshifting: Their innate power as an alien race and the source of their incredible infiltration skills.
- Well-Intentioned Extremist: Did evil things, but in the name of a conviction that they were given divine right to take the Earth as a new home for themselves, since they had tragically lost their old one. Also claimed using the Skrull Captain America that they were here to help humanity by ruling over them as the human race's superiors.
- What Kind of Lame Power Is Heart, Anyway?: This trope was their ultimate downfall. For all their incredible power and perfect replication of human minds and bodies, but the one thing they could never replicate is the power of the human will and not only that, they very unwisely underestimated it. Lampshaded by Captain America in "Secret Invasion".Cap: There's more to human beings than our bodies and minds... something you'll never understand... OUR SPIRIT! ''We never surrender! We never give up! EVER!'
Skrull Mockingbird (Queen Veranke)
Veranke is the Queen of the Skrull Empire and coordinates the secret invasion of Earth from behind the scenes. S.H.I.E.L.D. Agent Barbara Morse (aka Mockingbird) was captured by the Skrulls, and Veranke replaced her, thus getting the opportunity to manipulate her enemies more directly.
- Because Destiny Says So: She is confident that her invasion will succeed, since a prophecy foretold the Earth would be the Skrulls' new homeworld. Needless to say, she doesn't take it well when the invasion fails...
- But if you look at it a certain way, the prophecy came true. The Earth belonged to the Skrulls. But it didn't say how long they would have it...
- Big Bad Ensemble: Forms one with the Supreme Intelligence in Season Two, as the two of them are responsible for heading the Skrull and Kree Empires that generate the majority of that season's conflict.
- The Chessmaster: The leader of the secret invasion. Her plans to divide Earth's heroes using Paranoia Fuel have worked perfectly.
- Disc-One Final Boss: Her invasion is foiled halfway through the season, with the Kree and the Supreme Intelligence taking over as the villains.
- Faux Affably Evil: She masquerades as Mockingbird.
- God Save Us from the Queen!: She's quite sadistic, enjoying seeing Iron Man suffer.
- Green-Skinned Space Babe: When she revealed herself as Veranke to Skrull Captain America.
- Manipulative Bastard: The whole invasion worked through a massive Batman Gambit to disband the Avengers, use Nick Fury's own tactic against him, and take control of every major criminal, terrorist, superhero, and law enforcement organization on Earth. Not to mention using Captain America's image as a way to attempt to convince the Earth's people to surrender to extraterrestrial domination.
- The Mole: She is "working" for Nick Fury and brought the Skrulls to his attention.
- Royals Who Actually Do Something: She's the leader of the invasion and actively participates in it by acting as The Mole in Fury's inner circle.
- Smug Snake: All of the Skrulls have this to some extent due to their confidence their plan will work (which it very nearly does), but Veranke has this the worst. Even when the Avengers begin fighting back and exposing the Skrulls, she only smiles a smug grin and furthers their plans with no worry the humans will have any effect, outright stating that they cannot lose and that they're foolish for even trying. Needless to say, her arrogance comes back to bite her scaly green ass hard.
- Spared by the Adaptation: After the invasion fails, she is merely taken to 42. In the comic, she gets Killed Off for Real by Norman Osborn.
- Stripperific: In her royal garb.
- Villainous Breakdown: When the Avengers suddenly start gaining the upper hand, she loses her cool and orders a massive attack to wipe out humanity. Even after it fails, she tries a last stand while repeating: "This can't be... it was written..."
Skrull Madame Viper
The first Skrull that Nick Fury learns of. She was killed in combat against Mockingbird, revealing her true nature, and her body was retrieved surreptitiously by Nick Fury after Hawkeye's unauthorized invasion of HYDRA Island.
- Designated Girl Fight: Mockingbird catches her while assisting three guys (Hawkeye, Captain America, and Black Panther) in taking down HYDRA Island.
- Green-Skinned Space Babe: Like all Skrulls. Well, the female ones.
- Killed Off for Real: When last seen, she was lying motionless and unconscious on a cold slab and had reverted back to her natural Skrull form, which is what happens when they die. There's also Tony Stark's implication:Tony Stark: How do you even know that this is a Skrull? I'm assuming this one isn't talking.
Skrull Captain America
Avenger Steve Rogers was captured by Skrulls and replaced with a doppelganger, shortly after the Avengers overthrew Loki and returned to New York. This Skrull replicated Captain America's personality and skills almost perfectly, fooling all of the other Avengers for two months. Ultimately, the real Captain America defeated the Skrull in a duel, but the damage done to Steve's reputation took longer to repair.
- Cover Identity Anomaly: "Avengers, attack!"
- The Dragon: To Veranke.
- Early-Installment Weirdness: When the Skrull Cap first revealed his Skrull form in the first season finale, he had red eyes with black pupils.
- Easy Impersonation: Viewers can distinguish the Skrull from the real Captain America because the former wears the costume from the Ultimate Marvel universe, but none of the Avengers really questioned the costume change onscreen. (Hawkeye told Skrull-Cap that he liked his new costume, but didn't ask why he got one in the first place.)
- Evil Twin: Of the real Captain America
- Fantastic Racism: Towards the Kree, if his impetuous assault on Ronan the Accuser in "Welcome to the Kree Empire" is an indication. The other interpretation is that Skrull Cap knew that Ronan was on Earth to judge the worthiness of the human race to be included into the Kree Empire as a subject people once the Kree conquered Earth, and he therefore attacked to thwart the Kree's ambitions of getting their hands on Earth before the Skrulls. However, the look of sheer disgust and anger Skrull Cap makes leads one to believe that he just legitimately resents Kree like Ronan with a burning passion.
- I Gave My Word: Baron Zemo insists for Cap's assurance that the Avengers would not let the Enchantress kill him. Cap gives his word, but breaks it by refusing to activate the magic-neutralizer in time. He also kicks Zemo in the face afterwards.
- He also makes an empty promise to prove Hulk innocent of Red Hulk's crimes.
- Kick the Son of a Bitch: Kicks Baron Zemo in the face when he regains consciousness before anyone else in "Acts of Vengeance."
- Laser-Guided Karma: He's responsible for jailing Hulk by not clearing his name, which leads to the Out-of-Character Alert and ultimately his downfall.
- Luckily, My Shield Will Protect Me: Unlike the real Captain America, he uses a photonic shield created by Tony Stark. Skrull-Cap can increase its size depending on how many people he must protect.
- The Mole
- Mole in Charge: Once Iron Man tries to dissolve the Avengers, Skrull Cap holds Hawkeye, Wasp, and Hulk together as a team and assumes leadership of them.
- Out-of-Character Alert: Nick Fury finds it suspicious that when the Hulkbusters come to arrest Hulk for the rampage Red Hulk framed him of committing, Cap tells Hulk to let the Hulkbusters take him without a fight. Cap doesn't even try to tell the Hulkbusters that Hulk is innocent. Zemo also notices his unusually callous attitude and was the first to suspect that something was up.
- The Shadow Knows: No one noticed except the viewers, though.
- Take That!: Toward the Ultimate/Earth-1610 Captain America, considering he has the personality traits and costume of the Ultimate Cap and ends up being defeated by the 'original' Captain America (who is closer to the Earth-616 Steve Rogers).
- Wolverine Publicity: Appears on the cover of Disney's sixth DVD, which comprises entirely of episodes set after the Skrulls' invasion, possibly because his costume looks more like that of Marvel Cinematic Universe Cap.
Super Skrull (Kl'rt)
Kl'rt the Super Skrull is an incredibly powerful Skrull warrior who has the powers of The Fantastic Four. He tries to recapture all of the prisoners that Captain America frees, but they ultimately escape.
- Adaptational Villainy: In the comics, Kl'rt sided against the Secret Invasion, considering the Skrulls leading it to be dangerous fundamentalists. But here he sides with them.
- All Your Powers Combined: Since he has all the powers of The Fantastic Four.
- Smug Super: Just check his quote above. Though he still takes Captain America for a threat that needs to be removed, unlike the Skrull commander he worked under.
Other Super Skrulls
- All Your Powers Combined: Many different combinations between other heroes and villains make up the Super Skrull army, including Abomination/Whirlwind/Griffin, Spider-Man/Black Panther/Iron Fist, Grim Reaper/King Cobra, Giant-Man/Crimson Dynamo, and an X-Men powered one with Wolverine/Cyclops/Nightcrawler/Colossus.
- Elite Mooks: All have powers and all are considered the best of the Skrull warriors.
- Mythology Gag: Two of the Super Skrulls (other than Kl'rt) are actually from the Secret Invasion in the comics, those being the X-Men powered one and the one with Mr. Fantastic/Iron Man/Black Bolt/Dr. Strange as one for the Illuminati.
Two groups of Skrulls impersonated each of the Season One Avengers to advance the invasion. The first freed Captain America from his prison cell, so the aliens could learn from his performance how to break the human spirit. The second tried to trick Ms. Marvel into teaming up with them and invading Wakanda.
- Big Damn Heroes: As part of a plan to find out how to break the human spirit, Skrulls impersonating Iron Man, Thor, Hulk, Black Panther, and Hawkeye entered Captain America's cell on the Skrulls' spaceship, claiming to be Avengers coming to rescue him. Cap didn't take long to realize these weren't really his friends...
- Conservation of Ninjutsu: The first team was defeated by one man in under ten seconds. Admittedly, it was Captain America, and it may be justified if the impostors couldn't simulate the real Avengers' powers in that instance.
- Never Trust a Trailer: The original trailer for Season 2 showed many scenes of the Skrull Avengers, but played it out as though they were the actual Avengers.
- Distressed Damsel: Invisible Woman, in "The Private War of Dr. Doom".
- Green-Skinned Space Babe: Doctor Doom's computer portrays Invisible Woman as this while revealing her true nature.
- The Mole: The MO of the Skrulls.
- Not Himself/Herself:
- Invisible Woman reportedly tends to ignore Reed more often than Sue does. It's saying something that Reed notices this.
- Dr. Lyle Getz shows no concern at all in forcing A.I.M. agents to overload Earth's satellites until all life gets wiped out.