King Sombra’s dark influence was obliterated by the Crystal Heart, and the villain is well and truly dead. But when he attempts to steal the afterlife of an innocent victim, a human spirit is left hurtling towards Equestria, where this unfortunate soul is revived into the only vessel available: the reconstituted body of King Sombra himself.

Thus, a cheerfully oblivious alien is crammed into the form of the most evil and malicious being Equestria has ever known. Not that Shining Armor and Cadence know this, of course. As far as they are concerned, the King is back and he’s lost his fricking mind.

Click here for the TV Tropes page!

At first glance, Princess Luna's charioteers might appear to be little more than Royal Guards dressed in festive apparel for Nightmare Night. However, there is far more to the story than that - the Night Guards once played a pivotal role in the history of Equestria, and have sacrificed more for their beloved princess than most ponies are even aware of.

A dragon wanders through a starless night, into a land that banished him centuries ago. Never did he imagine he would return to the world that cursed his very existence, but when the sun and moon failed to rise one fateful day, something compelled him to begin the long journey home to the princess who shattered his heart.

After Big Macintosh helps the Mane Six out of a jam, he finds his ordinary life of
peaceful routine thoroughly disrupted by the various misadventures those crazy
ponies always seem to get themselves into.

Artwork provided by the talented Zemious

An alarm sounds. There's a planet nearby. I wonder if anyone can hear me.

(Post-Mass Effect 3)(FemShep)
When the Reapers were defeated, the galaxy believed that Shepard and Anderson were both lost in the final battle. However, the two long-time friends were also known for not letting death stand in their way.

Waking up, in the middle of a desert, on an uncharted planet they both embark on their strangest mission yet. Attempting to find their way back to the Human Alliance, a place called Canterlot may hold the answers they seek. But first, they had to get there while trying not to draw too much attention to themselves.

Too bad for Anderson since massive explosions and collateral damage followed Shepard wherever she went, without fail.

Crossover of My Little Pony and Mass Effect.
Cover image credit goes to: CSImadmax at http://csimadmax.deviantart.com/
Chapters 1 - 6 proofread by: http://www.fimfiction.net/user/GermanDash (Pre-March 2021 update)

Isolated from her friends and taken prisoner in the middle of a war, Twilight must deal with the very real dangers of being percieved as an enemy as well as the nightmares of her arrival on 'Earth'. Can she overcome her own fears and the fears of her captors? Will the wayward unicorn's assistance be a boon or a curse to the 'humans?' Most importantly, will she ever find her way home?

"In short, it's a story of friendship and plasma rifles, with the emphasis on the friendship. The characters are well written, the XCOM setting is fleshed out very well, and the story is compelling. If you love XCOM, you'll love the story, but even if you've never heard of it, it's more than worth giving the first 3 chapters a read.

There's excellent action later on, but the real strength lies in the collision between the friendly and naive world of Twilight Sparkle and the desperate world of humans fighting a losing war for survival and willing to do anything to turn the tide."

--Arzoo

(XCOM/FiM crossover)
(Cover art commissioned by a friend and created by the magnificent FoxInShadow!)
(Original cover art by the amazing Carnelian can be viewed here!)
(Gore tag for blood and some violence)
(Many thanks to the studius OminousTen, Arzoo, xXFluttershyForeverXx and finally Setokaiva for giving my rambles a once-over)
(Now with it's own TV Tropes page! Get to tropin' folks!)

Pincer is a changeling, a proud soldier of Queen Chrysalis. After the failed invasion of Canterlot, he finds himself trapped and at the mercy of Princess Celestia's Royal Guard. Believing that Celestia sees his species as nothing but soulless monsters, he prepares himself for the worst. The weeks crawl by, marked by an endless series of questions he will not answer for fear of endangering his friends and family at The Hive. As his nerves wear down and his interrogators learn just how ruthless he thinks they are, they have nothing to report but his belief that they will kill and destroy his kind without mercy.

Celestia steps in to prove him wrong, and what Pincer learns leaves him questioning everything he has ever known — but also gives him hope for what he'd never thought possible.

Cover art commissioned from http://www.demonkings.com.

Now with a TVTropes page.

When Twilight Sparkle slipped beneath the covers last night, everything had been fine. She had friends whom she loved, a teacher she adored, and a bright future ahead of her. But when she woke up, her blankets and quilts had been replaced by hospital gowns and padded restraints.

Everything is wrong and nothing makes sense; even her friends have changed. The doctors keep telling her that she is sick, that none of it was real and that it was all in her head. Yet she remembers a life far beyond the hospital walls. She couldn't have made it all up on her own. They must be lying… right?

Ask Asylum Twilight - Still updating regularly!
Equestria Daily
TVTropes
Asylum Fan Group
The Tartarus Project
Russian Translation
The Asylum 20,000 View Spectacular Stage Show!

Art:
Asylum Cover by conicer
Twilight and Twilight Smiles by dreamingnoctis
Mirror Twilight and Plague Doctor by Jaestring / BloodGoldWings
Twilight Smiles and Doctor AJ by conicer
Nurse Ratchet and Silas and What's in the mirror? by Archonix
Doctor AJ Sketch by Archonix | Colored and vectored version by ReFro82
Twilight's Asylum by Khan the Cake Lover
Smilight by HappySwitch
Twilight Waking Up by Dombrus
Fan Art by toxicdemon10
Asylum Twilight by Madness-With-Reason
Asylum Fluttershy and Asylum Ch 26 by Downburst-Backspace
Twilight and her Twin by v747
Birdgirl by sirValter

Readings and Videos:
Asylum Animated Trailer Video by formuladash
Reading by Gammarobot (SugarCubeRadio): All Chapters Here
Reading by Ender Brony: All Chapters Here
Reading by VisualPony: All Chapters Here
Reading by MelancholyIguana: All Chapters Here
Fan Trailer by Kaidan: Asylum FanFic Trailer Cuckoo's Nest

Sanctuary by Kaidan
Broadhoof Files: Dr. Humors by TypewriterError
Broadhoof Files: Corporal Phalanx Spear (Ret.) by Phalanx Spear
A Hearth's Warming Tragedy by Seven Fates

A special thanks to Breath of Plagues, Rex Ivan,
ChudoJogurt, Cynewulf, Death the Kid, Selbi, PrinceDolph, Blahman2816, Queue, and Gage!

Axan Zenith - Dr. Dreamer
Dratini4 - Way Finder
psychicscubadiver - Bright Mind
Velkaden - Dream Chaser
Reese - Silver Glow
Viola Heartstrings - Clover
Archonix - Spinney Whiteacre

They called it conversion. The last desperate act to save an entire sapient species from the spread an effect none could have predicted, one that threatened to slowly, painfully wipe every human from the face of the earth.

It was flawed.

A Conversion Bureau reimagining.