[Complete! With TVTropes apparently!]
Also, apparently, an animated trailer.

In a world of brass and steam, Twilight Sparkle had thought she had made a life-changing discovery with the invention of the telescope. For better or worse, she was correct.

Now her discovery has not only changed her life, but the lives of those she seeks out in her desperate attempt to contact the only other creature as lonely as Twilight herself.

It all would have been much simpler, but it had to be the one Twilight could only call The Mare on the Moon.

Decidedly not within walking distance, then.

[Featured on EQD before story was meant to be submitted. 4/03/2015]

[Editing team: Southpaw, Wolfvenom, Maskedferret, SwanSong and BluePaladin42, without whom this story would be a fraction of its current state.]
[Special thanks to Novel-Idea for the updated cover]

An MLP/Warhammer 40K Crossover

The Iron Warriors 38th Company has landed in Equestria, entrenching themselves like a barbed hook. They hunt the aliens of the Tau Empire, intent on destruction and pillage.
A small squad is dispatched on a reconnaissance mission, only to find that there is intelligent life on this world besides the feuding space-farers.
Will these improbably adorable and friendly equine aliens turn the damned warriors of Chaos from their blood-soaked path, cleansing them of their dark legacy with the magic of friendship and harmony?

No.
No, that isn't happening.
EXPLOSIONS!!

(Dark humor warning; limited grimdark themes)
(Cover art by Nicholas Kay)
(This series now has its own TVtropes page!)
(This story is a contestant in the Tournament of Canterlot, a charity event to raise money for Syrian refugees! Go here for details and donations!)
(Featured on Equestria Daily 8/20/15 )

Heartbroken from her friends and brother abandoning her at the wedding rehearsal, Twilight Sparkle retreats to a strange new world and is later followed by Spike and Rainbow Dash. Once there they encounter new races, strange technology, gain great power and see to the foundation of a new empire. But while there they experience constant warfare from many enemy factions that seek their destruction, turning the innocent ponies and dragon into naught but a memory. So now there is only one question: when they return to Equestria, will they come as peaceful diplomats, or conquerors?

Universe in set in a Halo/Warhmmer 40k/Star Wars mixed galaxy.

Halo is property of Bungie.
Warhammer 40k belongs to Games Workshop.
Star Wars is owned by Disney.

Not sure if the action sequences will actually be gorey, but the tag's there just in case.

Celestia has finally found her eternal partner in love. Twilight Sparkle, Element of Magic, savior of Equestria, and co-ruler of the nation. Celestia feels nothing but pride and love for her student, friend, and lover. However, a secret remains hidden in her heart, hidden from herself. Why did she choose Twilight, of all ponies, to be her student?

Unfortunately for her, Discord knows the answer all too well.

Got the art from the greatly talented StePandy. Go check them out for even more awesome art!

Thanks to my prereaders/editors Skeeter the Lurker, HellRyden, Vexine, Ghostwriter95, Cozmosus, Flint Sparks, Merc the Jerk and SpaceCommie!

Just for Harmony and the Sisters, Discord decided to take things a bit seriously the second time around.

Now seemingly unopposable on his Chaos Throne, King Discord has all of Equestria at his clawtips.

His very first decree? The very first royal act of chaos? The moment that may define his reign?

Pardoning Mane Six.

Wait, what?

Discord's reign will be filled with surprises, chief being how the draconequus is far from malevolent to those in his lands, despite what the ponies have been told. It seems that while Equestria belongs to Discord now, but he does play(mostly) responsibly.

And as time goes on, the appeal of Chaos can worm its way into most any heart.

NOTE: Not a tyrantlestia fic.

This story is a sequel to I'll Always be Here for You

A budding love, a new family.

Rescued from her horrible parents by Twilight and Rainbow, Scootaloo begins a long journey of recovery from the years of mental and physical abuse. Now Rainbow’s and Twilight’s adopted daughter, she looks forward to what the future has in store for her. However, Scootaloo's happiness and her life are at risk now that her parents have escaped from prison, fully intent on revenge.

Meanwhile, Rainbow and Twilight try to make their relationship work as they face the difficulties of raising a filly together. To accomplish their dream of a happy family, they all must face numerous challenges that will test the strength of their love and friendship.

Twilight Sparkle and her assistant Spike just came back from a lecture when they saw Starlight Glimmer in the throneroom. She held in her magic a scroll with a time charm.

Starlight Glimmer wanted to travel with this time charm and the map in Twilight`s castle to the past and change the destiny of Twilight and her Friends.

But something had gone wrong, because Sombra has dived has stolen the magic and used it himself to travel into the past. He wants to dominate his dark plan to rule Equestria.
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I apologize if you do not understand some. I have written this story with the google translator because I live in Germany and I'm not so good in English. I'm really sorry if this is the case.

Twilight becomes alicorn of the stars. This is sort of a problem, because Luna kind of already was alicorn of the stars. Oops!

TV Tropes

Now with an amazing YouTube reading by the equally amazing AShadowOfCygnus!

During its two year search for Shepard, the lone Geth traveled across the galaxy, exploring worlds both known and unknown. After a blind FTL jump to escape from an Alliance patrol, it found itself in a previously undiscovered system, a system without a mass relay and completely cut off from the rest of the galaxy. It touched down on one of the worlds, a garden-like planet, with the intention of gathering data on any flora and fauna that may have been present.

Instead, it made a remarkable discovery.

Edit at 8:10 AM on 8/17/2014: Scanning...Featured Box Achieved! This unit humbly thanks all organics and fellow synthetics for their support!

A big thanks to my bloody brilliant proofreader AShadowOfCygnus. Don't stop being classy, buddy.
NOTE: This story takes place years before the Return, back when Twilight was just a filly.
Disclaimer: I own nothing.
My Little Pony: Friendship is Magic belongs to Hasbro.
Mass Effect belongs to BioWare and Electronic Arts.

In the far reaches of Canterlot Castle, high above in the towers lived the archmage. Everypony knew her, yet few had met her.

Twilight Sparkle sighed, having teleported away another noble seeking favors before reaching the top of the stairs for the second time today. They never learned. As the archmage, she already dealt with political squabbles far too often without inviting them into her home. Aside from personal favors for Celestia, she did what was required of her position and then returned to seclusion and research.

The nobility grumbled that no archmage should be a commoner, and Twilight’s disrespect toward them proved it. Each and every time they were forced to bow to her, they hated what they saw: the position, the status, the deference.

Was she not powerful? Was she not great?

Twilight, now reading through dusty scrolls and long forgotten tales, wrote in her notes — notes gathering dust of their own. A brief thought flashed through her mind.

Am I not powerful? Am I not great?

And then Twilight picked up The Tale of the Royal Pony Sisters.

Defunct side stories told in Across the Boundary. They can still provide a little context, but when in doubt, the main story here is canon.

Cover art provided by Lafiir