Unicorns

Unicorns are one of several kinds of ponies that live in Equestria. They are characterized by their horns and their ability to perform magic.

Development
Unicorns had the ability to teleport magically or "wink out", but did not ordinarily have any other magical abilities.

Unicorns originate from the writings of Helenistic Period of Greek history. They were considered to be part of India's native fauna. During the Middle Ages, unicorns were linked to several animals, among them the rhinoceros, the oryx and the mammoth. Medieval legends relate that unicorns permitted virgins to ride on their backs, while subsequently killing imposters. In modern times unicorns have become associated with magic and beauty. Monoceros (Latin: Unicorn) is a constellation in the celestial equator, and one of the 88 modern constellations.

Depiction in the series
As the name suggests, all unicorns have a long horn protruding from their forehead which glows when their magical powers are used. Although they are associated with their magic, a unicorn's horn is strong and sharp enough to have mundane uses: one unicorn in Call of the Cutie uses it to pop balloons, and Twilight Sparkle uses it to charge an opponent on several occasions. Twilight Sparkle and Rarity are often seen using their intellects to compensate for their lack of physical strength, such as when Twilight earns fifth place in the Running of the Leaves in Fall Weather Friends and Rarity overcomes her captors in A Dog and Pony Show. It was stated in Boast Busters that most unicorn magic revolves only around their natural talents (e.g. their jobs, hobbies, etc.) as seen in Rarity's case, thus making unicorns like Twilight Sparkle unusual for having a talent that is magic itself. However, both Rarity (in The Cutie Mark Chronicles) and Twilight Sparkle (playing the role of Clover the Clever in Hearth's Warming Eve) have stated that Unicorn magic itself does not happen without reason.

Also, four times in the series, their magic has been cancelled out. The first is in The Cold Shadows of Hate Part 1, when Shadow uses Chaos Control removes the horns from Twilight Sparkle and Rarity. In Ponyville Confidential, Sweetie Belle simply kicks Rarity's horn to cancel out her levitation spell instantly, while in The Crystal Empire - Part 1, Shining Armor's magic is rendered ineffective by King Sombra's magic. Sombra's magic causes black crystals to grow on Shining Armor's horn, nullifying spell effects. The fourth and most recent is in Princess Twilight Sparkle - Part 1 where Rarity stops her haywire magic by licking her hoof and touching her horn, dispelling the magic in a manner not unlike snuffing a candle. The other pony races generally have difficulty competing with a unicorn's magical talent, as seen when Trixie easily bests Applejack and Rainbow Dash in a show of skill. This causes Rarity to state that only another unicorn could put Trixie in her place, although Twilight Sparkle is the only unicorn present able to outdo Trixie.

Alicorns

 * Main article: Alicorns

Faust intended Princess Celestia and Princess Luna to be the only Alicorns. They are called unicorns in the prologue in Friendship is Magic, part 1, and the princesses are called "Pony Princesses", including Princess Cadance; in A Canterlot Wedding - Part 1, Twilight Sparkle contrasts Cadance being a "princess" with herself being a "regular old unicorn"; the script for A Canterlot Wedding - Part 2, when naming Queen Chrysalis for the first time, refers to her as a "pegacorn". Despite these other terms, storyboard artist Sabrina Alberghetti calls the princesses "alicorns". In Magic Duel, the word "Alicorn" is used for the first time in reference to an amulet depicting a Pegasus unicorn. Twilight Sparkle's transformation and subsequent reappearance to her friends in Magical Mystery Cure is the first time any character is directly referred to as an Alicorn in the show.

Unicorn magic
Lauren Faust has stated that Earth ponies and Pegasi have passive forms of magic, but unicorns can actively perform magic. In a retelling of the history of Equestria in Hearth's Warming Eve, unicorns controlled the sun and moon before the rule of Celestia and Luna.

A common ability among unicorns is using telekinesis to levitate or move objects, as seen with Twilight Sparkle, Rarity, Trixie, and various background unicorn ponies. The ability to cast other spells varies widely and sometimes depends on the unicorn's special talent. Unicorn magic requires concentration and effort, as Twilight explains to Spike in Feeling Pinkie Keen and to Apple Bloom in Call of the Cutie. In Lesson Zero, Twilight says she needs a line of sight with an object to undo the spell she cast on it.

Colors of magic auras
When unicorns cast magic, it produces a colored aura around their horns and any objects their magic affects. The color of the glow surrounding objects affected by unicorn magic is inconsistent within the series. The color of the glow of incidental characters' magic is not consistent in this way and frequently differs from their eye color, as is the case with the exam supervisors and the waiters in The Cutie Mark Chronicles, for example.
 * Rarity's glow is light blue while her eyes are of a darker shade. However, it does match her eyeshadow. Rarity's glow in the first season also appears purple on certain occasions.
 * Trixie's glow is light pink, which doesn't quite match her purple eyes.
 * Flim and Flam's magical glow is colored green, matching their eyes.

This relationship between eye color and magic color does not hold for Twilight's and Celestia's magical glow either.
 * The color of Twilight's glow is inconsistent in the first season and more consistent in the second, turning magenta like the color of her cutie mark.
 * Similarly, whereas the color of Celestia's magical glow varies throughout season one, this glow is consistently yellow in Lesson Zero and A Canterlot Wedding - Part 2, like her cutie mark.
 * The addition of a yellow glow to Celestia's magic is one of the changes to the new opening sequence.
 * Queen Chrysalis, while disguised as Princess Cadance, uses magic that glows green. However, the real Cadance's magic glows light blue, consistently.
 * Twilight Sparkle and Shining Armor, as well as their mother Twilight Velvet, share the same magic aura coloration. Shining Armor has magenta-colored magic, whereas his eyes are blue. In Twilight and Shining Armor's cases, the magic glow resembles the most prominent color in their cutie marks.
 * Sweetie Belle's magic aura is a light green, matching her eyes.
 * Sunset Shimmer's magic aura is aqua, matching her eyes.

Baby unicorn magic
The episode Baby Cakes features a little baby unicorn named Pumpkin Cake, the daughter of Mr. and Mrs. Cake, who uses her magic unexpectedly when Pinkie babysits her and her Pegasus twin brother, Pound Cake. Rarity cautions the other ponies at the beginning of the episode that "baby unicorns get strange magic surges that come and go", and Pumpkin Cake experiences these surges when she's able to use her magic to teleport, walk through solid objects, levitate herself and other objects, and break the locks and chains that Pinkie put around the toy chest.

Residence
Canterlot is mostly populated by unicorns in its three appearances in Friendship is Magic, part 1, Sweet and Elite, and The Cutie Mark Chronicles. Notable exceptions are Hoity Toity and Princess Celestia's pegasus pony guards. Ponyville has its share of unicorns, more or less equally with Earth ponies and Pegasi. In Applejack's visit to Manehattan unicorns are only seen as waiters, and the rest of the ponies there are Earth ponies. Since they lack the natural ability to walk on clouds, they should not be ordinarily present in Cloudsdale, but Twilight Sparkle casts a spell on herself and her friends that allows them to walk on clouds and attend a competition in Cloudsdale in the episode Sonic Rainboom.

List of unicorn ponies

 * Amethyst Star
 * Berry Pinch
 * Berryshine
 * Blue Moon
 * Charity Sweetmint
 * Charm
 * Comet Tail
 * Cookie Crumbles
 * Diamond Mint
 * Dinky Doo
 * DJ Pon-3
 * Doctor Horse
 * Fancy Pants
 * Fancy Pants' entourage
 * Fine Line
 * Flam
 * Fleur Dis Lee
 * Flim
 * Gallant True
 * Golden Delicious
 * Holly Dash
 * Hondo Flanks
 * Inkwell
 * Jet Set
 * Joe
 * Junebug
 * King Sombra
 * Lemon Hearts
 * Lemony Gem
 * Liza Doolots
 * Lyra Heartstrings
 * Minuette
 * Neon Lights
 * Night Light
 * North Star
 * Peachy Pitt
 * Ponet
 * Pound Cake
 * Prince Blueblood
 * Pumpkin Cake
 * Rare Find
 * Rarity
 * Raven
 * Royal Pin
 * Royal Ribbon
 * Sapphire Shores
 * Sea Swirl
 * Shining Armor
 * Silver Spanner
 * Snails
 * Snips
 * Star Swirl the Bearded
 * Sunset Shimmer
 * Sweetcream Scoops
 * Sweetie Belle
 * The Pony Tones
 * Trenderhoof
 * Trixie
 * Twilight Velvet
 * Twinkleshine
 * Upper Crust