After strange occurrences with radios across the world Twilight does some research. What she finds, changes everything.

This story is a sequel to Headhunters

The headhunters came, saved the day, and then they left. But in their wake they not only left a pile of Covenant bodies – they left Princess Twilight Sparkle with a spark of wonder. An interest in the galaxy that surrounded her little home planet; an interest in the lurking dangers and the magnificent wonders of the universe.

Unfortunately it seems some of the danger and wonder is coming to visit Equis. So it’s time for the bookish shut in to throw herself into the galaxy to find the warriors who would help her defend her home.

Halo (non-canon) vs. My Little Pony (season 4) Crossover

Rated Teen for gratuitous swearing and violence.

War is ruin, predicted and then remembered as glory.

The Changelings and their vengeance-mad Queen grow ravenous in the south. Nations all around gaze hungrily at Equestria. In the north, beyond the Crystal Mountains, an unfathomable menace sends even the fiercest Diamond Dog packs fleeing before it. In Canterlot, a capricious Prince lusts for absolute power.

Against it all, Equestria stands toothless. Fearful for his country and thirsty for vengeance against Queen Chrysalis, Shining Armor desperately tries to convince Princess Celestia of the need for an Equestrian Army. Yet even as plans are made to march against the Changelings, the means for his triumph may have been delivered into the hooves of Prince Blueblood, who will risk everything to seize the crown he deems rightfully his.

Map
Royal Equestrian Army order of battle

PRINCESS TWILIGHT SPARKLE: DEAD AT 18

TELEPORTATION INVARIABLY FATAL, WARNS LEADING SCHOLAR

One look at the headline of the Canterlot Times and Twilight knew that she should have slept in today. But at least none of her friends would be silly enough to believe she was killing herself every time she teleported, right?

There is now a Spanish translation of this story, courtesy of Spaniard Kiwi

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.

A machine made for war awakes in a new world. Stuck in surroundings which puzzle it; can it, or will it be able to become something more than what it is?

Crossover with Keith Laumers Bolo-verse
Other tags include : Slice of Life, Possible Romance believe it or not! And a bit of humor.
Please beware of any spoilers in comments as well

This story is undergoing a massive rewrite. Expect everything to change soon.

A Russian MVD Spetsnaz team is sent smashing into the ground after the Mil Mi-24 they were in was knocked out of the air. A short time later, the crew and passengers wake up to find themselves in the wreck of the helicopter - but nowhere near Moscow.

As they desperately attempt to find out where they are, they will discover that they are not alone: Other humans have also found themselves in similar situations. However, these disorganized forces may soon be fighting for their survival, against an enemy that they could never have planned for...

The original version of the story, as published 2013-2015, can be found here for those that want to read it as it was. Editing on the original story was done by The Rainbow Brony, and I am thankful for the time that he put into the story to make it better than it would have been otherwise.

It has been weeks since the defeat of the Dazzlings, and Sunset Shimmer's friendships have only gotten stronger. Whilst finally relaxing in the times of peace, Sunset discovers an old enemy: Sonata Dusk. Strangely alone and apparently homeless, Sonata's luck seems to be at its all time low.
Seeing a little of herself in the former siren, Sunset embarks on a mission to help Sonata find friendship.

(For anyone who liked the old cover art, here's a side-by-side comparison of the old and new: http://daniel-gleebits.deviantart.com/art/Go-Compare-Twiddles-moustache-581352606 )

TV Tropes page: Feel free to add whatever tropes you find
http://tvtropes.org/pmwiki/pmwiki.php/Fanfic/TheEveningSonata

After surviving the bloody slaughter of his platoon at the hands of the invading Human forces, one stallion of the Equestrian Day Guard is put to the test as he finds himself hunted by an invisible but deadly foe. A sniper follows his every move as he tries to escape the silent and terrifying opponent.

PS: I hit the 'Popular' section for the first time, yay!

(Thanks to Darwin4 for offering to be the editor for the story, you're the best! Also, if anyone is interested in making some cover art for me, then go ahead! Until then its staying as it is. If you do, I'll credit you and make sure my readers know of your contribution.)

Princess Celestia and Princess Luna are leading together a combined Army of several different equestrian Races against an supposedly terrifying and unfeeling Enemy.

What kind of Threat are our beloved Princesses are really going to face?

A Warhammer 40K/MLP:FIM Crossover.

Special Thanks goes to ARchy4288, Tyrannosaurus_Tux and AlicornPriest for Editing, Proofreading and otherwise helping.
I can only recommend those guys.