"It's so nice to see you again!" said the thing that was not Celestia. "Oh yes, I know who you are, Twilight Sparkle. I had a taste of your magic the first time we met. Mortals forget things so easily, I find. Allow me to refresh your memory: you tried to kill me. But you failed, Twilight Sparkle. You only mostly killed me. And I guess that makes you one very unlucky little pony."

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?

An object of unknown origins crash lands in the no-pony's land between Equestria and Gryphon territory. Princess Luna and Twilight Sparkle race to beat the Gryphons to the crash site, but discover more to the crash than they originally thought.

Spartans never die, they're just missing in action. This has never been more true for Jorge-052 as, after activating the slipspace drive that was supposed to kill him, he is instead flung into a strange world where war is but a distant memory. Will the aging soldier be able to adapt to this new peaceful planet? Or will his only salvation be found in finding a way back to his own chaotic universe?

(It's my first time, so be gentle)
Now featuring a TVTropes page by Sabo88

A visitor arrives in Equestria, bearing a wealth of knowledge and a troubled past. The Mane 6 are quick to befriend the stranger, who helps them to discover what they truly value in life, and how to achieve it.

But learning to overcome their fears and achieve their desires comes at a steep price, paid by their innocence.

In the year 2745, humanity's grasp of the sciences has advanced to an almost unfathomable level. Sub-space matter transfer technology grants almost instant access to countless worlds across thousands of light years. These advanced machines are not without their limits. The vast energies which constantly course through them put immense strain on their inner workings, and it is your job as a highly trained maintenance tech to fix what breaks. On your way to a typical repair job things take a turn for the decidedly weird, and you suddenly find yourself thrown into a world both familiar and alien. Will you ever learn the cause of your displacement, or will you be forever subject to the whims of this strange new world?

One thing does become quickly apparent. The citizens of your new home are frightened to learn of your species' carnivorous ancestry, the signs of which are made painfully obvious with every toothy grin. What's a pony to do when these ancient surges of primal fear sow a quickly growing seed of carnal need? A tumultuous avalanche of the deliciously devious awaits.

A slightly more realistic take on the "Human in Equestria" story concept.

... For a given value of "realistic."

Okay, it's barely realistic but it is a hell of a lot of fun...

Now with an image graciously provided by Page Turner, and an audiobook version narrated by multifanficaday and if you prefer it in German, FrankyDoodle has got you covered!

And a TVTropes Page!

Last Featured: 11/26/2019! Thank you so much!

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 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

“History is written by the victors.” ~ Winston Churchill

Welcome to the new Equestria: Several decades ago it spanned a continent, now it encompasses an entire world due to an unknown phenomenon that occurred many years ago. Equestriani towns and cities now dot the planet. What many of its inhabitants try to forget though is that many of these cities were built over older cities that belonged to a now-extinct race: humans.

Crystal Clear, a fledgling researcher with a fascination of these beings, intends to publish a book; a comprehensive take on their race. His task is not an easy one as the event all those years ago has ensured that nothing tangible of their era remained. The only way for him to gain any information on mankind is via old unofficial accounts and interviewing the 'newfoals' and anypony who lived with humans back then. But the latter are far and few... and those who had agreed before are now mysteriously refusing to comment. Why?

In the midst of this, Crystal's grandmother passes away, leaving him several memory orbs of her times with humans. Is this the break that he has been searching for? Will he finally come to an understanding of this elusive species or will he learn of something that he wasn't meant to know?

This story has been reviewed by The Equestrians Critics Society. See the full review here.