Humanity sends its first manned spacecraft to another solar system using FTL travel. Their mission is to establish a research base to study possible life on this extrasolar planet. However things are not as they first thought as they find intelligent life is already there.

Please Note: This is a Half-Life Crossover, so there will be gore.... and language... and bad puns/references (Ever seen the Minds?)... Just a warning.

The timeline from the original Half-Life game is split just before the final teleportation scene. Gordon finds himself trapped in Equestria, a seemingly peaceful dimension inhabited by three separate races of sentient ponies. However, the peace is shattered when elements of both Earth and Xen begin to bleed through the second inter-dimensional rift Gordon had created. (The first being the initial resonance cascade).

Every schoolfilly has heard of the Federation - the tall, mysterious, magicless beings from another world, who visit only rarely and briefly; waiting, they say, for 'stable planetary political unity'.

This is the story of when they first visited Equestria; of early contact between the Princesses and the Federation. It is also the tale of how Princess Luna, with some help from the House of Sparkle, managed the first fully Equestrian warp jump; and of how Spike became the first dragon in space.

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Additional note: There is an alternate ending for this story, which can be found over here. It follows on directly after the chapter titled Further Communications (and there is a note in the author's notes for that chapter to that effect, with another link).

The reasons for the split are contained in the comments to this story. (Note: Said reasons contain spoilers)

Luke Skywalker crash lands on Equestria. Twilight Sparkle, Spike, and their friends help him repair his droid and his ship, but in the process he develops friendships with them. Will he return to the fight against the last remnants of the Empire, or will his new friendships, and his feelings towards the Princess of Friendship be enough to make him stay?

The first couple of thousand words of this story were a collaboration with Short Stories, but the rest is me. Proofread by Arian Blaze plus the people of the Crossover Skype Chat.

See if you can also spot references to Doctor Who, Star Trek, The Hitchhiker’s Guide to the Galaxy, and Back to the Future.

Part 1- The first story of how captain Kirk and Celestia got to know each other. Something happens that almost causes the downfall of the Federation.

Jean-Luc Picard has explored strange new worlds and boldly gone where no one has gone before, but when he and a number of his crew are transported into a world of magic and colorful quadrupeds by a familiar foe, they begin to...ugh, I'm no good at this. Tl;dr the TNG crew is transported into Equestria.

Alright, this is another blast from the past. In fact, when I started writing this, the Season 2 premiere hadn't even aired. Obviously, I added more on since then. Rated T just in case of Star Trek-y things.

Somehow (super powers that aren't magic) Q managed to drag Jean-Luc Picard through a temporal distortion into the magical land of Equestria. Meanwhile, Discord somehow (super powers that are magic) escaped his stone prison, indisposed Celestia and Luna (big surprise) and banished Twilight. This is hers, his, his, and his, story of meetings, trust, redemption, and success (but who's?). Of course, I'm just making this story up as I go. New description to follow, maybe.

The Federation Starship Voyager is lost in the Delta Quadrant, 70000 Light Years from home.
They stumble upon Equestria.

Events may develop in a disastrous way.

A MLP/Star Trek Voyager Crossover
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Edited by Gammablitz
Thanks to ReiDuran for permission to use his art.

While on a routine mission the Enterprise is called to check out an anomaly in deep space.
However, through a chain of events, that are completely not Kirk's fault, he and a red shirt fall into the anomaly and awake in Equestria. As ponies.
Can Kirk handle being in a land of ponies and magic? How will he fulfill his contractual obligations to some how rip his uniform shirt? Will Ensign Ricky live to tell the tale? What is Harcourt Fenton Mudd scheming about while in the brig? What is Sulu doing in his off time? Why am I asking you this? And most importantly, can the crew of the Enterprise bring them back, or even survive without Kirk?

Cross over with classic Star Trek
This story takes place a week after the counter clock incident from Star Trek The Animated Series,
And between seasons Two and Three of My Little Pony Friendship is Magic

In the far future, the Federation and Starfleet face total annihilation. A disease has spread through space threatening to destroy every star it touches. Chaos descends upon the galaxy, shattering the peace forged by worlds that were once united by freedom. But all is not lost. A last-ditch effort is launched to save the dying stars: a mission to explore a new galaxy.