Princess Celestia: Goddess of the Sun, ruler of Equestria, beloved Princess of ponies. She is loved by all, and loves all in return. A calm and wise ruler, she sits on the throne in Canterlot, maintaining peace and harmony throughout the land.

What most don't know is that her past is much darker: She was once a commander of legions, a warrior and scientist of unmatched skill. Thousands of monsters and abominations fell to her forces, slain in the name of an old leader, one entombed within his own throne. Free of her old form, free of the powers of Chaos, she was cast into a new realm, in a new form, with a new lease on life.

She is the God Emperor, Eternal Ruler of Equestria and Lord of the Imperium of Man.

Has a TvTropes Page. Please contribute.

Comments contain spoilers. YOU HAVE BEEN WARNED!!!

This story is a sequel to Stardust

Times are changing for Equestria as Twilight’s return brings with it news of people and cultures from beyond the peaceful world everypony knows. Aid and volunteers are freely offered to help the besieged humans of Earth because every Equestrian knows that’s what good friends do. Unfortunately, making friends can also have the unintended consequence of making enemies.

When the monsters besieging the humans strike at Equestria with a level of brutality not seen in over a thousand years, the cry for help is sent to all the kingdoms of the world. Honored allies step forth to fulfill ancient treaties and oaths. Enemies, old and new, bury their grievances. An alliance never before seen in Equestria will be created to combat the monsters from the void.

And because of these events, a grim but welcome sibling to the XCOM project is born.

(XCOM/FiM Crossover)
(Sequel to Stardust, which I recommend reading before starting this. Fortitude Amicitia and Broken aren't required reading but are supplemental to the storyline)
(Gore tag for blood and violence)
(Alternate Universe tag because of the divergence from canon that Stardust has caused)
(Uses elements of Season 4)
(Coverart produced by the amazing Carnelian!)
(Many thanks to Arzoo, BradTheBrony, Vandenbz and Setokaiva for prereading!)
(As of 03/07/2016, the prereading team consists of Arzoo, BradTheBrony, Noble Cause and Metallusionsismagic!)
(Complete with it's own TVTropes page as part of the Stardust continuity. Could use some updating!)
(Character tags will be added as chapters are added!)
(Featured 5/12/2014! Thanks folks!)
(Possible spoilers in the comments! BEWARE!)

The following transcripts are of a journal found in Ponyville on April 16th of this year. The last recorded contact with the town had been 3 days prior, on the 13th, when a team under orders from Princess Celestia was sent to look into several missing pony reports in the area. When another group of investigators were sent on the 16th, the town was found deserted. The journal’s owner is believed to be the princess’s personal student, Twilight Sparkle. None of the town’s inhabitants have been located in the weeks since.

Readings:
Nimbus Productions
Scribbler Productions

I highly recommend both of them.

A print version of all the stories in this series can be found here.

There has always been a little voice in Twilight Sparkle's head, whispering dark musings to her. And until her brother's wedding, she has managed to push those bitter thoughts away and focus on the good. She forgives and forgets and holds onto hope.

But when her friends turn their backs on her and her brother cuts her from his life, Twilight finds herself alone, with only the little voice to comfort her.

And it is through anger and hate that has been repressed for so long that Twilight finds the power to rise up. Harmony and Friendship have only brought her pain and suffering. It is time for her to embrace her dark side. No longer will she worry about what others think. Twilight is going to live her life how SHE chooses: without friends, without family, without love and without harmony. She is going to cut loose, have fun, and screw what others think.

For her friends and family, it will soon become apparent that if they don't find a way to mend the damage they've done to the lavender mare...Twilight Sparkle might be lost to them forever.

Thank you to everyone that got this story as one of the Featured Stories here on the site!

The TvTropes Page can be found here: http://tvtropes.org/pmwiki/pmwiki.php/FanFic/FaithAndDoubt

Cover created by the amazing FerGarcia220

This story is a sequel to The Rainbow's Surprise

On the day of Fluttershy and Rainbow Dash's wedding, Princess Celestia left Twilight a message saying that she should prepare herself if something happens. The next morning, Twilight awakens to find that all of Ponyville has succumb to a blinding fog. She must now travel a monster-filled town in search for her teacher and friends and try to return Ponyville back to the way it was.

This story is a sequel to Too Shy for a Rainbow

If you liked this fic, check out the awesome Audio Dub version of it by The Lost Narrator!:
https://www.youtube.com/playlist?list=PLnqCBZacYIwK0xcHv85Lke-xFf5V9p7R4

It's been a month since Fluttershy and Rainbow Dash started dating. Everything was going fine until Fluttershy started experiencing horrific nightmares that started keeping her up at night. Looking for answers, Rainbow Dash, Fluttershy and Pinkie Pie seek out Twilight. But when the three mares find themselves within the world of Silent Ponyville, will things turn out for the better? Or will things end in tragedy?

Sequel: http://www.fimfiction.net/story/14866/Silent-Ponyville%3A-Reunion

Pinkie Pie is being tormented by horrific nightmares. Unable to deal with it by herself anymore she seeks out Twilight's help, but will it have been the best decision when she finds herself alone in an abandoned, fog filled Ponyville?

Sequel: http://www.fimfiction.net/story/4676/Too-Shy-for-a-Rainbow

There have been a LOT of high-quality readings of Silent Ponyville, but this one is my personal favorite:
https://www.youtube.com/playlist?list=PLGh01rbB4o3xoSV7a6Omc-UJROXHRZ1Hv

The mane six take shelter in a place that is, for now, safe from a disaster occurring outside.

This gruesome tale of violence and death is not recommended for colts, fillies, or the faint of heart.

Twilight Sparkle never was a Unicorn and she didn't even know it.
What happens when her true heritage comes to light? Will she willingly embrace it? Or will she be forced to?

Beware of spoilers in the comments!

Edited by uTTerAbsurdity, Zervziel, Stormwatch and Gwenio

Cover art by the talented Cartoonlion and colored by the equally talented Stormwatch, original can be found here

Click here for the Tvtropes page

Daring Do cannot believe her luck when she is asked to help explore the most ancient tomb known to ponykind. But terrible danger awaits her, for beneath the earth rests something beyond equine understanding.

Warning: comments contain ending spoilers.

TVTropes page.
Alternate ending by Duplex Fields.
Archived in the Pony Fiction Vault.
Reviews:
One Man's Pony Ramblings
Louder Yay
PresentPerfect
The Royal Guard
Cleverpun's Critique Corner
The Goodfic Bin