Aliens come to Earth all the time in the Marvel Universe. It's basically the Grand Central Station of the universe. The Kree, the Shi'Ar, the D'Bari, the Badoon and plenty more have all come to Earth for various reasons, but there are few alien races as hostile and antagonistic towards humanity as the Skrulls. These shapeshifting aliens have been trying to conquer the Earth for ages, with only Marvel's greatest heroes standing between them and the people of the planet. The Skrulls look to play a big part in Marvel's upcoming Empyre event, this time seemingly teamed up with their ancient enemies, the Kree.

RELATED: Avengers: 10 Things To Know About The Kree Skrull War Before Empyre

In honor of their role in that upcoming event, this list is going to take a look at some of the worst things that Skrulls have done in the Marvel Universe.

10 Sabotaging Human Space Programs

In the '50s, humanity was taking their first tentative steps into space and the Skrulls decided that they weren't about to let that sort of thing happen. Humanity going to space would make them develop better technology that would allow them to fight back against the Skrulls if the aliens ever chose to invade.

So, the dastardly shapeshifters attacked the space programs of the US and Soviet Union, leading to a battle between the 3-D Man and the Cold Warrior. This would be the opening salvo in the Skrulls' long time battle against humanity.

9 Trying To Turn The Public Against The Fantastic Four

The Fantastic Four were the first superheroes of modern times and protected the Earth from all kinds of threats. They were the first line of defense for humanity before the Avengers were even an alcohol-induced fantasy of Tony Stark. The Skrulls knew this and decided they had to do something about it.

A group of Skrull agents used their shapeshifting abilities to impersonate the Fantastic Four and commit crimes, trying to turn the public against the team. The FF were able to overcome the Skrulls and clear their names, though, leading the Skrulls to figure out a new way to take their revenge.

8 Creating The Super Skrull

The Skrulls' shapechanging abilities made them dangerous foes, able to infiltrate their enemies, learn their secrets, and turn them against each other. However, there were some limits- they couldn't copy the powers of the being they were impersonating. After encountering the Fantastic Four, they knew they'd need more than their usual abilities.

Using samples taken from members of the FF, they modified one of their soldiers, Kl'rt, giving him all the powers of the team, and the Super Skrull was born. Kl'rt would go on to become one of the most dangerous Skrulls in the universe, working to expand his people's influence by any means possible.

7 Sinking The Raft

The Raft was a special prison used to house the supervillains of the Marvel Universe. In Brian Michael Bendis's inaugural New Avengers storyline, "Breakout," Electro would attack the Raft on the order of some mysterious benefactors, busting the prison wide open and allowing the supervillains inside to escape. Of course, it also had the inadvertent effect of getting a new team of Avengers together, which definitely wasn't something the people who hired would have wanted.

RELATED: 10 Characters That Could Be Skrulls After Avengers: Endgame

It was later revealed that the Skrulls were behind the whole thing, as they were trying to spread as much chaos as possible for a much bigger scheme (more on that later). And this wasn't all they would do...

6 Taking Over S.H.I.E.L.D.

Nick Fury and a group of heroes had gone on a secret mission to overthrow the acting Prime Minister of Latveria. They succeeded, but when it was found out what they did, Fury was forced to go into hiding for breaking international law, leaving a power vacuum at S.H.I.E.L.D. He was replaced by Maria Hill, who, while competent, was not nearly as good as Fury.

Under her nose, the Skrulls began to infiltrate S.H.I.E.L.D., taking over top spots and using the organization to persecute the heroes of the Marvel Universe. Again, this was all part of their larger plan (keep reading), as it sowed the seeds of distrust between the heroes and S.H.I.E.L.D.

5 The Illuminati

Marvel's Illuminati, Consisting Of Namor, Reed Richards, Doctor Strange, Black Bolt, And Iron Man

The Illuminati was a secret group of superheroes- Iron Man, Reed Richards, Professor X, Black Bolt, Namor, and Doctor Strange- who came together to make secret decisions that would steer the superhero community. After the Kree-Skrull War (yeah, that's coming up), the Illuminati traveled to the Skrull homeworld and warned them to never attack Earth again. The Skrulls were able to overwhelm the six men and take them prisoner.

RELATED: 10 Things Every Marvel Fan Should Know About The Super Skrull

They used this time to experiment on them, taking samples from each member that would come in handy later when they sprung their master plan.

4 Kree Genocide

The Kree and the Shi'Ar don't have the same legacy of hatred that the Skrulls and the Kree did, but that didn't stop the two races from going to war. The Avengers would try and intercede in this war in the "Operation: Galactic Storm" (named after the real-life U.S. led Operation Desert Storm, the first war in Iraq) storyline. The Skrulls would get involved because, well, they hate the Kree so much.

They would supply the Shi'Ar with a Nega-Bomb, which the Shi'Ar would detonate, killings billions of Kree and wrecking the Kree homeworld of Hala.

3 The Warskrulls

After the Shi'Ar-Kree War, the Skrulls would begin to attack the Shi'Ar more and more. They would dispatch the Warskrulls, a group of genetically modified Skrulls that used a device called the Nexus Amplifier to take the powers of the beings they impersonated.

During this time, they would take over members of Starjammers and commit genocide against Shi'Ar affiliated races, trying to turn the galaxy against the Shi'Ar. One of them was able to impersonate Professor X, copying his telepathy and taking control of Empress Lilandra. Eventually, Deathbird and the X-Men would defeat the Warskrulls and restore the Empire's good name.

2 The Kree-Skrull War

The Kree and the Skrull had been at each other throats' for centuries. Eventually, though, the two sides would come to blows and declare war on each other. The conflict would last for centuries, as the two races become more and more militaristic. Eventually, Earth would get pulled into the conflict, as both races had been observing and interfering with humanity for years.

The Avengers would get involved and the reason both races were interested in humanity was revealed- they were both at an evolutionary dead-end, which was why both races were always coming to Earth and experimenting on humans.

1 Secret Invasion

After the Kree-Skrull War, Galactus destroyed the Skrull homeworld, pitching the Empire into disarray. A faction of Skrulls, led by the new Empress Veranke, would go to Earth in an effort to conquer the planet so the Skrull could have a new capital for their empire. This plan would take a while and multiple steps to put into motion (as illustrated in several entries on this list).

Once they got it into full swing, they were able to overwhelm the conventional forces of the human governments and used the divisions they had sewn between the Earth's heroes to almost succeed in their plans before the heroes banded together and stopped them. It was the Skrull's most successful attempt at conquering Earth.

NEXT: 7 Skrulls We Hope to See In The MCU (& 3 We Hope We Won't)