At the height of the EndWar, a Ghost team has orders to track down a madman who has kidnapped some of the United States' top scientists. However, when it turns out that the madman has used them to build a portal to escape from the world's ongoing onslaught, he runs through, forcing the Ghost team to follow through and take him down. In the aftermath of events, the Ghosts realize that they have no way to return home, and find themselves in a middle of a conflict that calls upon their talents to protect Equestria.

Crossover Material: Ghost Recon/MLP
Rated Teen for Graphic Violence and Language

Earth events take place in an alternate reality EndWar/Ghost Recon: Future Soldier.
Future Soldier technology is only drawn from initial previews of the game (exoskeletons, crosscoms, MR8s, rocket pods, active camouflage).

Inspired by the heroics of the mysterious mare known as the Stable Dweller, Silver Storm, a guard of the town of Marefort, decides to go on a daring mission to rescue her captured brother. Of course things rarely go as planned and her attempts at heroism drags her into a tangled web of plots and conspiracies as warring factions vie for control over the last great city: Dise.

Spanish Version translated by Spaniard-Kiwi: https://www.deviantart.com/spaniard-kiwi/art/Fallout-Ecuestria-Heroes-996263393

Canterlot... For centuries, Canterlot was the shining gem of Equestria, the pinnacle of pony society. Now, it’s a reminder, a bleak and monolithic warning to the world. 

Changed by the chemical and technological poisons that plague the mountain, an abomination of nature, I wander the greatest disaster Equestria has ever seen. 

... I will escape eventually, and when I do, I hope my friends still see me as Twilight Sparkle, and not the monster that hides among the ruins. 

'Have you heard about a new major expedition into the Zone? Technically, they're environmental researchers from the U.N., but that's just on paper. Sure, they've got a couple four-eyed scientists, but one look at all the others tells you they're seasoned fighters. Oh, and dig this; They're not using guides.' - Hog the Mercenary

The Tourist, a veteran stalker hired by the United Nations as an escort, finds himself working with the International Scientific Group, a collective ranging from hardened experts to frail researchers. After gaining clearance from the Ukrainian government for another expedition, the United Nations arms and readies their best field operators, the ISG.

Deployed into the Zone, these interlopers reach their destination, a large Space Bubble with an unknown exit. Quickly, the group enters the Bubble before a large emission and arrive within a forest, where they set up their mobile lab and temporary base of operations to make the best opportunity of an new anomalous area inside of what they assume to be Zone. However, as time passes and new encounters are made, it becomes more and more obvious that they aren't in the Disaster Zone anymore. Pressure begins to mount as the Zone's influence begins to leak into the forest, along with old dangers.

Without a doubt, the group as well as the Tourist will have to struggle to survive against the dangerous flora and fauna that sees fit to consume them. Of course, those become less attention-worthy once sentient, small horses come to investigate the stalkers and scientists, who are easily seen as a threat. The Zone is cruel, but new encounters can be crueler.

NOTE: This is a S.T.A.L.K.E.R. crossover that relies heavily on lore. The ISG faction was only mentioned, mostly cut from the series, but is still canon. Takes place roughly during the end of ShoC.

The Princesses find an alien creature barely clinging to life at the scene of a terrifying crash. Can the Combined Power of the Elements of Harmony save it, or more importantly, should they save it? Will the arrival of this strange creature tear Equestria apart?

TV Tropes
https://tvtropes.org/pmwiki/pmwiki.php/FanFic/Article2

Crossover with the Dresden Files. Sequel to Forever!

For his first task as the new Winter Knight, Harry must travel to the land of cute little cartoon ponies to stop a plot by the Order of Blackened Denarius that threatens both Earth and Equestria.

Warning: Includes massive spoilers for the Dresden Files series up through Ghost Story.

Apparently, I wasn't the first human to walk the face of Equestria. In fact, there were a million before me. But for a different purpose, they existed. And to resolve their problems and the past of their creator, I was brought into this world. There was no time for rejoicing or playing around. A duty had been bestowed upon me, just another Human in their eyes, to bear the power that was locked away inside every one of us. To find what was lost to Earth for so long.

But hey, it's Equestria. Things can only look up from here, right?

... right?

The star system Omega Centauri was just another oddity on a map to scientists in the not too distant future. However when they found the star was orbiting an earth-sized, earth-like planet instead of a black hole as its motion had suggested, a mission was scrambled to investigate this most unusual of celestial behaviors.

Hamstrung by politics, and nearly crippled before it began, the 'Lone Ranger' mission was reduced to just one crew member and left to his own devices.

These are the logs of Arrow 18 and its lone commander. This information is classified TOP SECRET by the Global Space Agency.

Do NOT tell the princess.

The royal court of Canterlot welcomes its newest member with open forelegs: the human philosopher Voltaire, from Earth.

On Earth, Voltaire is known as the greatest enemy of tyranny in the history of literature, and a legend in his own mind.

On Equestria, the court betting pool is giving him a week before the Princess banishes him to the Moon.

Note: This story doesn't have sequels per se, but there are a couple of short follow-ups set in the present day ("Parade Coverage" and "Secret Histories"), and a prequel of sorts in "At the Inn of the Prancing Pony".

TV Tropes page.

While pursuing a splinter of Hive Fleet Behemoth, Captain Sicarius and the Ultramarines 2nd company are caught in a warp storm that carries them and their prey to an unknown planet. Meanwhile, Princess Luna notices something strange in space that could spell danger for all of Equestria. Swept up in a war between the terrifying Tyranid swarm and the vengeful Ultramarines, the ponies must fight for their lives in a war that spans a galaxy.

Thanks to thirdstring_overlord and GiftedMonster for proofreading my newer chapters. thirdstring_overlord also writes an excellent 40k crossover that needs some fans. Go check it out!

Disclaimer: I do not own My Little Pony: Friendship is Magic and Warhammer 40k. They are the properties of their respective owners.