Alicorns

Alicorns are ponies who have both a unicorn horn and Pegasus wings and, depending on the depiction, also have Earth pony power. They are styled as royalty. Meghan McCarthy, one of the show's head writers, says that the title of "princess" is one that is earned in Equestria.

The third season episode Magic Duel marks the first use of the term "Alicorn" in the series, and in Magical Mystery Cure the term is used for the first time to directly refer to winged unicorns, previously referred to as unicorns in earlier seasons' episodes Friendship is Magic, part 1 and A Canterlot Wedding - Part 1.

The regal sisters
Princess Celestia and her younger sister Princess Luna are introduced in the first episode in a series of medieval-like drawings with a narration that says there were "two regal sisters who ruled together and created harmony for all the land," and that "the elder used her unicorn powers to raise the sun at dawn. The younger brought out the moon to begin the night." Lauren Faust commented that Princess Celestia was originally supposed to be Queen Celestia, the highest authority with no parents who outrank her. Her status was later changed to "princess" at Hasbro's request. Faust has stated that Celestia embodies the traits of all three pony kinds: Earth, Pegasus, and unicorn. a writer and consultant for both series has stated that the inclusion of Earth was "an intentional improvement" they made on Series 2, "based on feedback and it being one of those 'could be canon' sorts of things that just plain makes sense. Faust has suggested that there is more to Princess Celestia than has been depicted of her in the series, and that she wanted Celestia to be "mysterious and hard to understand".

Princess Cadance
The first half of the second season finale, A Canterlot Wedding - Part 1, introduces Princess Cadance. She is Twilight Sparkle's foal-sitter in Twilight's flashback, and she becomes her sister-in-law after marrying Shining Armor in A Canterlot Wedding - Part 2. Various promotional materials, including a New York Times ad, A Canterlot Wedding - Part 1's Hubworld, iTunes, and Netflix summaries, the back cover of the DVD Royal Pony Wedding, and the home page of Treehouse TV's Royal Wedding Contest site, state that she is the niece of Princess Celestia. A blurb on one of the toy sets featuring Cadance says that she and Shining Armor "lead the Crystal Empire together!" Indeed, a background pony proclaimed her as "The Crystal Princess!" at the end of The Crystal Empire - Part 2. In Enterplay's trading card series, Series 1 lists her pony type as both Pegasus and unicorn but not Earth, and Series 2 lists her pony type as all three; a writer and consultant for both series has stated that the inclusion of Earth was "an intentional improvement" they made on Series 2, "based on feedback and it being one of those 'could be canon' sorts of things that just plain makes sense."

The book Twilight Sparkle and the Crystal Heart Spell states that Cadance was born a Pegasus and became an Alicorn later.

Queen Chrysalis
Queen Chrysalis, only seen in the episode A Canterlot Wedding - Part 2, was described in her debut episode's script as "a GANGLY BLACK PEGACORN with a gnarled black horn." She and the other changelings were designed by Rebecca Dart, the main character designer for season two. Rebecca was inspired by the work of manga artists Junko Mizuno and Hideshi Hino, and after reading the name "Chrysalis", she "figured [Chrysalis] should be insect-like." The changelings are referred to as a different species in the show and also as ponies on page 53 of the guidebook The Elements of Harmony.

Twilight Sparkle
Twilight Sparkle is introduced in the show as a unicorn, and she even calls herself a "regular old unicorn" in A Canterlot Wedding - Part 1, to which Princess Cadance replies "You are anything but a regular old unicorn." According to Meghan, "princess [in Equestria] is a designation that’s earned, not freely given and though princesses have specific leadership roles in pony society, being one really means 'being a good pony who shares the gifts that they have been given with others.'" Twilight surprisingly becomes a princess and gains wings in the ending of a movie, The Equestria Sonic Boom.

Twilight Sparkle and the Crystal Heart Spell
The chapter book Twilight Sparkle and the Crystal Heart Spell describes Twilight's new status in chapter 1, "A Crown Achievement": "Twilight had received her very own set of wings. Real Pegasus wings! She was officially a part of a special breed of pony called an Alicorn. This meant that Twilight was now able to harness the magical powers of the Unicorns, the flight abilities of the Pegasi, and the strength of a good, true heart of an Earth Pony."

The Alicorn Amulet
The Alicorn Amulet is an amulet which features the image of an alicorn. Trixie uses it to become a "highest level unicorn" and gain immense magical powers and antagonize the citizens of Ponyville in the episode Magic Duel. Twilight Sparkle finds out that only the wearer can remove the amulet and tricks Trixie into removing it with a fake amulet of her own in a magic duel.

List of Alicorn ponies

 * Princess Celestia
 * Princess Luna
 * Princess Cadance
 * Twilight Sparkle