Starlight Glimmer

Starlight Glimmer is an Equestrian unicorn and the main antagonist of the Season 5 premiere of My Little Pony: Friendship is Magic. Her back story and plans of taking away ponies' cutie marks and creating a utopia-like community where all ponies have equal-sign cutie marks to represent 'being equal' have yet to be revealed. All that's known is that she is the ruler of the utopia, steals the cutie marks of the Mane 6, and has a vastly different and rather sinister view on friendship and the individual talents that make Equestria's ponies so special.

Revealing the map
At Twilight Sparkle's castle in Ponyville, Twilight wonders about the castle's appearance following the defeat of Lord Tirek. As she and her friends sit in their thrones, their cutie marks begin to glow, causing lights from their thrones to shine upon the star-shaped platform in the center of the room. The castle suddenly comes alive to construct an elaborate holographic map of Equestria.

Floating images of the Mane Six's cutie marks point toward a location far off from Ponyville, and the six friends believe that the map is beckoning them in that direction. As Spike stays behind to plan a hoofball weekend with Big McIntosh, Twilight and her friends set out on a road trip.

Village of odd smiles
After riding the Friendship Express to the end of the line, the Mane Six find a village in the middle of nowhere, where all of the houses—with the exception of one—are arranged in two parallel rows. The ponies cautiously approach the village and discover that all of the ponies living in it bear strangely perpetual smiles (which raises Pinkie Pie's immediate suspicion) and have the exact same cutie mark: a black equal sign.

As they enter the village, the Mane Six are warmly greeted by the villagers, much to Fluttershy's delight. Two stallions named Party Favor and Double Diamond meet them personally, noticing that Twilight is an Alicorn princess and that they all have unique cutie marks.

Twilight asks if there has been any trouble in town lately, of which Double Diamond states there hasn't ever been any. The two stallions decide to take the ponies to meet the village's founder Starlight Glimmer.

Starlight Glimmer
At Starlight's cottage, the Mane Six are introduced to Starlight Glimmer, who happily welcomes any pony that wants to experience what she calls "true friendship." She explains that her village is unique in that no one has special talents. Starlight gives the ponies a tour of the village in a big musical number, during which she explains that harmony in the village in predicated on equality—no one is special, no one argues, and everyone is equal.

When the song ends, Starlight and the villagers invite Twilight and her friends to join their society and give up their cutie marks—a sentiment and philosophy that Rainbow Dash openly mocks. The others are equally skeptical, and Starlight leaves their decision to stay or not entirely up to them. As Double Diamond sees to the Mane Six's needs, Starlight walks away, eager to spread her sinister message of equality to the rest of Equestria.

Big Brony is watching you
As the six friends continue to take in what the village has to offer, Twilight finds it inconceivable that a pony's cutie mark can be taken away. Rarity is repulsed by their questionable fashions, and Rainbow Dash is uncomfortable with their constant staring; Fluttershy is the only one keeping an open mind.

The friends sit down for lunch, and a baker named Sugar Belle notices them bickering, asking if their friendship is ending. They explain to Sugar Belle that it's natural for friends to disagree; this, coupled by the Mane Six's unique cutie marks, earns Sugar Belle's interest. She asks them to meet with her in private after they have lunch. Thinking that they're being watched, Twilight and the others have Pinkie Pie eat Sugar Belle's horrible tasting muffins and nonchalantly enter Sugar Belle's house.

In Sugar Belle's basement, the Mane Six meet with Sugar Belle, Party Favor, and Night Glider, who express a great interest in the ponies' cutie marks and yearn for their own. When Twilight asks how a cutie mark is taken away, Night Glider explains that Starlight Glimmer removes them with the "Staff of Sameness" and stores them in a cavern vault.

The cutie mark vault
Starlight Glimmer leads the Mane Six outside the village, pleased by their interest in the cutie mark vault. Twilight believes that the castle map brought them to the village in order to return the villagers' cutie marks. Inside a cave, they discover a large collection of cutie marks stored inside glass casings and a two-pronged staff standing upright.

Starlight asks the ponies how they learned about the vault, and Pinkie Pie inadvertently reveals that a pony in the village told them about it. Realizing that the friends' presence is a threat to her perfect society, Starlight springs a trap on them, and the villagers surround them. Using the Staff of Sameness, Starlight rips the Mane Six' cutie marks from their bodies, replacing them with black equal signs, and places the cutie marks in the vault.

With the ponies now stripped of their talents, Starlight says they'll learn how much better their lives will be without cutie marks. The episode ends on an overhead shot of the villagers standing around the Mane Six in a equal sign formation.

Paradise Lost
Following the loss of their cutie marks, the Mane Six are locked inside one of the village houses as unwilling permanent residents. As a result of their talents being taken away, Rarity has lost her sense of fashion, Fluttershy is unable to communicate with animals, Applejack has lost her country-style mannerisms, and Pinkie Pie is less cheerful. Twilight Sparkle, curious about Starlight Glimmer's Staff of Sameness, tries to think of a way to escape and eventually suggests pretending to accept the villagers' way of life. Because Fluttershy has been the most optimistic about the village since their arrival, her friends decide she is the only one whose pretending will be believed.

Fluttershy the mole
Starlight Glimmer lets the friends out of the house and asks if they are ready to join her society. The Mane Six once again refuse, saying that friendship between ponies cannot be forced. Starlight prepares to lock them up again, but Fluttershy speaks out, wanting to join her. Twilight and the others are locked inside the house, and Starlight welcomes Fluttershy—on one condition: give up the names of the ponies who spoke with her in secret and told her about the cutie mark vault. Before Fluttershy is pressured into outing her new friends, Party Favor speaks up, taking all of the blame and insisting he was acting alone. Starlight Glimmer locks him up with Fluttershy's friends as punishment. Party Favor despairs that it's only a matter of time before Twilight and her friends have all accepted Starlight's way, but they are certain that Fluttershy will come through. As Fluttershy's new home is built, she stays in Starlight Glimmer's house in the meantime. Once night falls, Fluttershy sneaks out to retrieve the cutie marks from the vault. She notices Double Diamond bringing the Mane Six's cutie marks to Starlight's house in jars. Starlight expresses particular interest in Twilight's cutie mark—the cutie mark of a princess. Fluttershy spies on Starlight and sees her trip over a bucket of water. As she cleans herself up, Fluttershy makes a shocking discovery: Starlight's equal sign cutie mark is fake!

Starlight exposed
The next morning, Starlight asks Twilight and the others once again if they're ready to join. They say nothing, and Starlight prepares to lock them up again. Party Favor is released when he shows remorse for his actions. When Twilight shows interest in joining Starlight's society, Starlight reasserts that happiness can only be found in equality. With this, Fluttershy attempts to expose Starlight's secret by dousing her in water. Starlight avoids getting completely wet, but some of the water splashes on her and causes her makeup to run. Party Favor notices this and uses a rag to reveal Starlight's real cutie mark underneath her fake one, much to the shock of her followers. Despite Starlight's efforts to save face, the villagers are upset that she lied to them. With her perfect society and plans now ruined, Starlight runs to lock herself inside her house. As the villagers go to retrieve their cutie marks from the vault, the Mane Six approach Starlight's house to retrieve theirs.

Pursuing Starlight
Using the Staff of Sameness (revealed to be nothing but a hunk of wood), Double Diamond shatters the vault's glass covering, and the cutie marks fly back to their respective owners. Meanwhile, Starlight takes the Mane Six's cutie marks and escapes through a secret passage under her bed. With the villagers' help, the Mane Six break into Starlight's house and follow her through the secret passage. They see Starlight fleeing toward the mountains, through which a network of caves would guarantee her escape and the loss of the Mane Six's cutie marks for good. Using their rediscovered special talents, Party Favor, Sugar Belle, Double Diamond, and Night Glider pursue Starlight Glimmer through the mountains, eventually cornering her just outside the caves and burying her in snow. The jars containing the Mane Six's cutie marks shatter, and their cutie marks are finally restored. Twilight and her friends catch up to confront Starlight Glimmer one last time, with Twilight protecting Party Favor and the others from a retaliatory attack from a furious Starlight. Despite Starlight's assertions that she gave the villagers "real friendship," Twilight speaks of the friendship she shares with her friends and how more genuine it is than Starlight's. In her desperation and fury, Starlight teleports away to an unknown location. Party Favor and the others thank Twilight and her friends for helping them rediscover their true selves.

Mission complete
The villagers celebrate the return of their cutie marks and true selves, giving real smiles instead of fake ones. The Mane Six's cutie marks start pulsating, and they sense that their job in this village is complete and that the castle map is calling them somewhere else. Before they leave, they decide to join in the villagers' partying for a little while.

Role in the SAF series
Starlight is expected to return, this time with help, and more details into the reasons behind her motivations behind her actions, and a much more unpleasent past.