Skrull

The Skrulls are a race of shapeshifting and technologically advanced extraterrestrials. They are the arch-nemesis of the Kree in centuries-long war, the Kree-Skrull War.

History

Over the course of history, they developed the ability to shapeshift into anything or anyone they want. They also fought the Kree for centuries.

The Skrull's homeworld Skrullos was destroyed by Galactus. This was happened as a prophecy foretold it would. A second foretold that the Skrulls would claim Earth (which was not true).

As the Kree sets their eyes on Earth, the Skrulls follow the same thing. They began infiltrating every human organization and groups on the planet, taking out and replacing each targeted member without being suspected.

It is unknown if they can be detected by human technology or instincts, but it is proven that Doctor Doom's advanced technology can detect a Skrull in disguise as he found out that Invisible Woman was indeed a Skrull posing as the real one. Baron Zemo knew something was wrong with Captain America, but before he could finish off him, the Skrull knocked him out.

They also have very advanced alien technology and weaponry almost equal to the Kree in their war for centuries.

Powers and Abilities

The Skrulls can shapeshift into any human or any superhero and supervillain as well in their infiltration on Earth to pave way for their invasion. They can also mimic their voice as well to prevent suspicion from other individuals.

Skrulls are shown to have enhanced speed, strength and durability, which is why Captain America was one of the easiest to replace since his powers are similar to them.

It is unknown how they duplicate a person's powers and abilities if a Skrull doesn't naturally have them (possibly using mutation or technology) such as Invisible Woman's shielding abilities and invisibility.

Weakness

Despite their morphing ability, they can still be seen using Earth and other alien technologies. Also if knocked out some or all Skrulls may revert fully or half way from their disguised forms. They can also slip out that they're imposters for reasons such as; actions, personality and memories (since a question or something else may be based on the person's past). Some of the Skrulls are very weak.

Notable Skrulls

Skrull Avengers:

Super-Skrulls:

Groups Infiltrated by the Skrulls

S.H.I.E.L.D. - Veranke (Skrull Queen), Clay Quartermain (Skrull)
S.W.O.R.D. - Henry Gyrich (Skrull)
Avengers - Captain America (Skrull)
Fantastic Four - Invisible Woman (Skrull)
HYDRA - Madame Hydra (Skrull)

Super-Skrulls

For the Skrull Empire military are a handful of Skrulls that are genetically enhanced with the powers of several superpowered and technical advanced people from Earth. The first Super-Skrull was Kl'rt, the rest were on the secret invasion mission, but they were all eventually captured and send to the super Prison 42.

Super-Skrull	Powers	Copied from
	Bodily rotation Super strength	Whirlwind Abomination Griffin
	Scythe	King Cobra Grim Reaper
	Super strength Electric generation	Thor
	Pyrokinesis	Human Torch
	Optic blasts Sharp claws	Cyclops Wolverine Nightcrawler Colossus
	Elasticity Energy blasts	Mr. Fantastic Iron Man Black Bolt Doctor Strange
	Super strength Enlargement	Crimson Dynamo Ant-Man Klaw
	Stealth	Spider-Man Black Panther Iron Fist
	Rock-like arms	Thing
	Rock-like arms	Thing
	Pyrokinesis	Human Torch
	Super-speed	Quicksilver

Gallery

Trivia

Captain America, was the only one to see through the Skrull's disguises without the tell-tale green eyes, and when a group of Skrulls imitate the Avengers, stating that he knows "How stupid do you think I am?" that they were imposters.
Iron Fist, Luke Cage, Ms. Marvel, Spider-Man, Thing, Vision, War Machine and Wolverine were the only the Avengers the Skrulls didn't shapeshift or impersonate.