Princess Celestia

Princess Celestia is larger than most ponies, with four exceptions being Nightmare Moon, who is about the same size until she reverts back to being Princess Luna, Trouble Shoes,[8] Steel Buns, and Twilight as a fully-grown Alicorn in the future. As with regular unicorns, when Celestia casts magic, a magic aura surrounds both her horn and the objects her magic affects. The color of this glow varies: for instance, it is blue in A Bird in the Hoof, pink in The Cutie Mark Chronicles, and white in Griffon the Brush Off. In The Return of Harmony Part 1, it is blue when Celestia opens the door to the vault, pink when she levitates the empty box the Elements of Harmony are supposed to be in, and blue when she drops the box. The glow is yellow in the remastered title sequence introduced with Lesson Zero,  as well as in that episode itself and all the second season episodes that follow it. Her tail and mane have a natural flowing motion, even when Celestia herself is not moving, but they stop doing so when Celestia is weak, as in A Canterlot Wedding - Part 2, unconscious, as in Princess Twilight Sparkle - Part 2, magic-less, as in Twilight's Kingdom - Part 2 and The Ending of the End - Part 1 and Part 2, or covered in slime, as in Make New Friends but Keep Discord. Celestia is introduced in the prologue of the first episode, depicted in a series of medieval-style drawings with a narration that says that "two regal sisters who ruled together [...] created harmony for all the land," and that "the eldest used her unicorn powers to raise the sun at dawn; the younger brought out the moon to begin the night."

The narration continues: their subjects, the ponies, played in the day but "shunned" the night and slept through it, which made the younger "unicorn" grow bitter, eventually refusing to lower the moon to make way for the dawn. Her bitterness "transformed her into a wicked mare of darkness: Nightmare Moon." The elder sister reluctantly harnessed the power of the Elements of Harmony and banished her "in" the moon for 1,000 years, maintaining harmony in Equestria by taking responsibility for both sun and moon.

The day of Nightmare Moon's return is also the 1,000 year anniversary of the Summer Sun Celebration, so Princess Celestia sends Twilight to oversee the celebration's preparations, which are being held in Ponyville, and encourages Twilight to "stop reading those dusty old books" and make some friends, much to Twilight's surprise.

Celestia is expected to appear at Ponyville's pavilion, but she goes missing and Nightmare Moon appears in her place instead. Celestia doesn't reappear until Nightmare Moon is defeated and transformed back into Princess Luna at the end of the second episode by Twilight and her friends. Princess Celestia offers her younger sister a chance to rule by her side again, and she accepts

In one alternate timeline in The Cutie Re-Mark - Part 1, Celestia wages a war against King Sombra and his Crystal Ponies, leading the royal guards and Wonderbolts into battle. In another alternate timeline in The Cutie Re-Mark - Part 2, Celestia is banished to the moon by Nightmare Moon. In a third alternate timeline, Celestia and Luna are reduced to being Discord's personal entertainment. Celestia describes more of her history in The Return of Harmony Part 1. She tells Twilight Sparkle and her friends that before Princess Luna and she stood up to Discord, he ruled over Equestria, keeping it in a state of unrest and unhappiness. Celestia goes on to describe that after seeing how miserable life was for Earth ponies, unicorns, and Pegasi alike, she and Luna discovered the Elements of Harmony and defeated Discord, turning him to stone. Discord's spell is later broken because, as Celestia explains, "Luna and [herself] are no longer connected to the elements." In The Crystal Empire - Part 1, Celestia describes how she and Luna worked together to defeat King Sombra, turning him into a shadow and imprisoning him in "the arctic north." The Summer Sun Celebration is first mentioned in the first episode. Twilight reads of the legend of the Mare in the Moon, who is set to return and bring everlasting night "on the longest day of the thousandth year"–the summer solstice–since her defeat, which is also the thousandth year of the Summer Sun Celebration. Princess Celestia sends Twilight to oversee the preparations for the celebration in Ponyville, where it's being held this year, also telling her to make some friends while she does that. Nightmare Moon claims to have been imprisoned for a thousand years, so this indicates that the first celebration happened after Luna was imprisoned. It is a celebration of Celestia imprisoning her and restoring the sun to Equestria During a party, Spike reminds an irate Twilight that the ponies have to stay up all night in order to witness Princess Celestia raise the sun. Later, at the Ponyville pavilion, Mayor Mare holds a brief speech and introduces Princess Celestia, but she turns up missing, and Nightmare Moon appears in her place. Only at the end of the following episode does Princess Celestia reappear with the defeat of Nightmare Moon, and the sun subsequently rises. The Summer Sun Celebration is featured again in Twilight Sparkle's flashback during The Cutie Mark Chronicles. Twilight describes it as "the most amazing, most wonderful thing" she'd ever seen, which made her want to study as much as she can about magic. The event itself takes place in Canterlot, where eight royal guards play a fanfare for Princess Celestia, who comes on stage and flies up, raising the sun behind her.

In the two-part season four premiere, the Celebration is featured and mentioned. Unlike the previous Celebrations, this represents not the defeat of Nightmare Moon but the return of Princess Luna. In The Summer Sun Setback, the Celebration is held for the last time, as Celestia and Luna feel no need to continue it after they retire, and Twilight creates a new holiday to replace it: the "Festival of the Two Sisters".

Princess Celestia refers to Twilight Sparkle as her "most faithful student" in the first episode, and Twilight is very proud of this fact. At the end of the second episode, Celestia tasks Twilight with staying in Ponyville with her friends and writing a weekly report about her studies of the "magic of friendship", which Twilight usually sends via Spike. These letters typically serve to illustrate each episode's moral for the show's viewers. During a flashback in The Cutie Mark Chronicles, Princess Celestia witnesses Twilight's rare magical talents and takes her as a protégé. Lauren Faust has suggested that there is more to Princess Celestia than has been depicted of her in the series. Relating to the events in the flashbacks in The Cutie Mark Chronicles, Celestia sensed that Twilight Sparkle was connected to the Elements of Harmony and arranged the dragon-hatching test for her; the time travel events of My Little Pony: IDW 20/20 follow. Celestia then raised and trained Spike, and subsequently assigned him to be Twilight's assistant;[9] Celestia presides over the wedding of Princess Cadance and Shining Armor in A Canterlot Wedding - Part 1 and Part 2, and monitors an anonymous threat that was made against Canterlot. The threat turns out to be an invasion by the changelings and their queen, who was already in Canterlot impersonating Princess Cadance. However, through most of the two-part episode, no one except Twilight suspects there's something wrong with Cadance. When Twilight brands the fake Cadance as "evil" at the wedding rehearsal, Celestia is greatly disappointed by her actions and agrees with Shining Armor's suggestion for Twilight not to bother coming to the wedding. Celestia sternly tells Twilight, "You have a lot to think about," before walking out on her with the others. However, after the exposure and defeat of Queen Chrysalis and the wedding ceremony, Celestia commends Twilight for persisting in the face of doubt and following her instincts in bringing Princess Cadance back, reaffirming their good relationship. In a flashback in Celestial Advice, Celestia sees Twilight progressing in her studies, but not so much in her social life, which leads her to contemplate how to further her studies. This leads her to her decision to send Twilight to Ponyville, a decision that she is, at first, rather hesitant about.

Celestia has been present during an episode in a few cases, allowing for Twilight Sparkle or another pony to deliver the report to her in person. She arrives for a scheduled royal visit in Swarm of the Century, and meets the six main ponies outside of Ponyville where Twilight makes her report. She comes to celebrate the Running of the Leaves in Fall Weather Friends, and Twilight makes a brief report about friendship being more important than a competition. She also attends the Best Young Flyer competition in Sonic Rainboom, where Rarity delivers the report to her directly. She is present for a royal visit in A Bird in the Hoof, so she hears Twilight Sparkle's intended report from Fluttershy.

Celestia makes a surprise cameo at the end of Feeling Pinkie Keen, dropping out of the sky to grab Spike's letter and then taking off just as quickly, confirming another one of Pinkie Pie's twitchy tail predictions.

Celestia is asked to come to Ponyville by Spike in Lesson Zero, after Twilight, fearing that being unable to send a friendship report will have dire consequences, enchants a doll, causing all of Ponyville to fight over it. Celestia arrives and undoes the spell, then sternly asks Twilight to meet her at the library. Despite Twilight's fears, Celestia does not reprimand her, telling her that she should only send a friendship report if she learns a lesson. She also decrees that Twilight's friends may also send her friendship reports.

Celestia makes a brief appearance in Sweet and Elite, showing Rarity to the room she will stay in while visiting Canterlot. She also displays awkwardness at Rarity fawning over her in thanks. At the end of the episode, she hears Rarity's friendship report. She next appears in It's About Time, passing by the "Star Swirl the Bearded" wing of the Canterlot library. She shows no signs of objection to seeing Twilight who had made an elaborate show of sneaking in, and compliments Twilight for her new hairstyle. In Magical Mystery Cure, Princess Celestia appears in a starry realm with Twilight Sparkle, revealing that she had sent Twilight the spell book of Star Swirl the Bearded as a test, which Twilight had passed by creating new magic. Just as Celestia starts singing, dozens of images float by, depicting Twilight's lessons and everyday studies, and she tells her about how it is time for Twilight to fulfill her destiny. Twilight, now having been transformed into an Alicorn, frets that she will no longer be Celestia's student. Celestia reassures her that she will still be her student but in "a different way" - that Celestia and the other princesses will also be learning from Twilight now, as well. She then arranges a coronation ceremony for Twilight, to crown her as Equestria's newest princess. In The Beginning of the End - Part 1, Celestia and Luna announce their decision to retire as rulers of Equestria, and have Twilight and her friends rule in their place.

However, in The Beginning of the End - Part 2, when King Sombra returns from the dead to take over Equestria, and he destroys both the Tree and the Elements of Harmony, Celestia and Luna return with Star Swirl to stop the Everfree Forest from going out of control again, so that Twilight and the others could stop Sombra. Ultimately, they decide to hold off on their retirement to give Twilight more time to prepare to rule.

In The Last Problem, Celestia officially turns control of ruling Equestria over to Twilight and retires to Silver Shoals with Luna.

Princess Celestia acts as a mentor to Twilight Sparkle. She often does not directly state her goals but rather gives the advice to help her student find the answers she needs. For example, she wrote a letter prompting Twilight to make friends in Friendship is Magic, part 1 when her goal was for Twilight Sparkle to find the Elements of Harmony. Despite being royalty, she often encourages her subjects to relax through the use of jokes and gentle questions. She also shows great patience with any inappropriate behavior towards her, as seen when Pinkie Pie snatches a cupcake from her at a party in A Bird in the Hoof. Princess Celestia displays a fun-loving side when she chuckles at the bottle of disappearing ink sent to her by Twilight in Griffon the Brush Off. In A Bird in the Hoof, while sipping from a constantly refilled cup of tea, she pretends to sip from her already full cup, causing Mr. and Mrs. Cake to overfill it. She watches with a smile on her face when Pinkie Pie devours one of her cupcakes, while Mrs. Cake gasps and drags Pinkie away. Celestia tells Twilight and her friends in The Best Night Ever, after they ruin the Grand Galloping Gala, that she always found the Gala awful and she was hoping they would liven it up. In Make New Friends but Keep Discord, Celestia invites Discord to the Gala for this same reason, and by the end of the episode, she declares it to be "the most fun Gala in years." While kindhearted and slow to anger, Celestia's patience does have its limits. When faced against the threat of Discord's return in The Return of Harmony Part 1, Celestia wastes no time in demanding that Discord return the stolen Elements of Harmony. Also, in Lesson Zero, when Spike makes her aware that Twilight inadvertently unleashed mass chaos onto Ponyville in her obsessive attempts to find a friendship report to send to the Princess, Celestia personally intervenes to undo Twilight's out-of-control spell. She sternly orders her student to a private meeting to discuss her actions but remains understanding, and at the insistence of Twilight's friends she agrees not to punish Twilight, instead asking them all to send her friendship reports only when the lessons make themselves apparent to them. In A Canterlot Wedding - Part 1, after Twilight furiously accuses imposter Cadance of being evil, Princess Celestia, along with the others, makes clear her deep disappointment in her student and walks out on Twilight after Shining Armor and the other ponies. But in A Canterlot Wedding - Part 2, while displaying righteous rage to the newly exposed Queen Chrysalis, she eventually commends Twilight for her instincts that told her the imposter Cadance was evil. Celestia can also be very forgiving. She does not admonish Fluttershy for taking Philomena without asking in A Bird in the Hoof. As mentioned above, she does not punish Twilight for the chaos she caused in Lesson Zero. In Keep Calm and Flutter On, she firmly believed that Discord could be redeemed, in spite of the trouble he had caused in the past.

She mentions that fall is one of her favorite seasons in Fall Weather Friends while at Ponyville to celebrate the Running of the Leaves.

In Between Dark and Dawn, Celestia shows a liking for exciting activities while on her vacation with Luna, such as ziplining and diving into the ocean, and shows boredom when Luna takes her to the theatre, or an art museum. During the song Lotta Little Things, she displays a love for stuffed animals, and later in the episode, is revealed to have trouble with maps, and suffer from alektorophobia (a fear of chickens). The episode A Royal Problem reveals a potential evil alter-ego for Celestia named Daybreaker, self-described as "the better, prettier, and more powerful version" of Celestia. This version of Celestia is considerably arrogant, power-hungry, and destructive. She boasts that she doesn't need Luna or anyone else, claims that she should have destroyed Luna instead of banishing her to the moon, and dismisses the notions of balance and harmony in favor of ruling over all.

Daybreaker harnesses more of the sun's power than Celestia does, allowing her to breathe fire and generate intense, burning light.

Daybreaker briefly reappears with Nightmare Moon in a vision shown to Twilight by King Sombra in The Beginning of the End - Part 1