The royal court of Canterlot welcomes its newest member with open forelegs: the human philosopher Voltaire, from Earth.

On Earth, Voltaire is known as the greatest enemy of tyranny in the history of literature, and a legend in his own mind.

On Equestria, the court betting pool is giving him a week before the Princess banishes him to the Moon.

Note: This story doesn't have sequels per se, but there are a couple of short follow-ups set in the present day ("Parade Coverage" and "Secret Histories"), and a prequel of sorts in "At the Inn of the Prancing Pony".

TV Tropes page.

It occurred one peaceful night. Half of Equestria awoke to the sound like a double-shot thunderclap. A percussion heard in the skies and rattling windows from Apploosa, to Canterlot, to Ponyville. Nopony knew what it was or what it heralded for the world as it drew a line across the nation.

For Twilight Sparkle, this isolated incident might have faded from memory after a time, if not for the strange rumors of a creature sitting on the hill on the outskirts of town.

These are her thoughts given written form. These are Sparkle's Notes.

Report EVERYTHING to the Princess.

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.

Equestria is a bright and shining kingdom. Its residents are content and safe in their idealic lives, thanks to the efforts of their benevolent princesses. And it has been as such for centuries. ...Or so everypony has always thought. But when an ancient sarcophagus is dredged up off the coast, Manehatten- and Equestria at large- will have to face the truth that there was something older in the world. A civilization and predators that moved through its shadows.

For before there was a world of harmony....there was a World of Darkness.

Now with cover art by Jake Was Here!
And fan art by CyanJames2819!

Octavia has a musical history and a side to herself she'd rather not have to explain outside of Ponyville. Inside Ponyville... well, everything was fine until she spotted Vinyl Scratch. What was she doing here?

Don't panic, Octavia! Don't freak out, don't lose your mind, don't....
Oh well.
(And check out Goombasa's excellent dramatic reading!)
Cover by Page Turner.

An ancient enemy has escaped their bonds and threatens to destroy the entire world in a black night of chaos and uncreation. What Equestria needs is Twilight Sparkle and the Elements of Harmony.

Unfortunately, what Equestria is getting is Princess Luna's rather dangerous-sounding 'Doom Patrol'.

Luna! Derpy! Princess Erroria! A weird-looking cyclops! They and the rest of the animation error ponies must race to save Equestria from the doom that awaits. But it's a task they can't possibly hope to achieve.

Because their enemy is... Nobody?

[NOTE: This story is very loosely inspired by Grant Morrison's 'Doom Patrol' comics from the 80s; absolutely no knowledge of it is needed to enjoy this, so don't get scared off!]

What if Nanoha never became the White Devil?

Twilight Sparkle, as everypony knows, is a magical pony by nature and profession. However, even she is confused when she encounters a mysterious ferret and an equally mysterious jewel. Forced into conflict by a monster attack, Twilight releases the power of the jewel, summoning the device known as Raising Heart.
Tasked with the retreival of a set of mysterious artifacts known as the Jewel Seeds, Twilight and her friends face an entirely new set of challenges. Unbeknownst to them, however, forces outside of Equestria are moving to claim the very same artifacts they now hunt.

A crossover with Magical Girl Lyrical Nanoha, with an equine twist!
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A sequel has begun. Go Here For Magical Pony Lyrical Twilight A's

Magical Pony Lyrical Twilight by PurpleProse is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Sweetie Belle gets a 'love at first sight' crush on a pegasus known as Show Tail, who seems far more interested in everything else but her. Dealing with one's first crush is hard, when you have to beg for his attention. But if you persevere, just maybe, you can win a heart. Oh the woes of young love. Hope you like this better! I know I do!

'John Smith' has settled in Ponyville with his wife and two daughters for many peaceful years. When the TARDIS gets a temporal distress call, Doctor Whooves and his family find themselves lost in time. Now Derpy must contend with not only monsters and maniacs, but the future and past versions of her husband!

Humans.

Truth or myth? Ancient lost civilization or just an old pony's tale?

No pony has ever seen one, and most haven't even heard of them. But Lyra knows that these wonderful creatures are more than just old legends, and she's going to find out... and possibly drive her roommate insane in the process.