Princess Twilight Sparkle is a lavender alicorn pony (previously a unicorn) who is the main protagonist of the series. She has a cutie mark of a 6-pointed magenta star with a white one behind it and 5 more smaller ones at each end of the magenta star. She is the sister of Shining Armor, and sister-in-law to her former foalsitter, Princess Cadance. She is the protégée of Princess Celestia. Twilight studies extensively and has "unusually powerful" magical powers. She tries her best to impress Celestia but has a tendency to overly analyze and become excessively worried over situations which she assumes will lead her to be seen as having failed.

As the "Princess of Friendship", she represents the Element of Magic and her goal is to spread the magic of friendship all over Equestria. Because she considered studying to be more important than friendship, Princess Celestia sends her to the town of Ponyville to learn the importance of friendship accompanied by her assistant, Spike. After staying in Ponyville for a while she decides to stay there and study friendship with her mentor's blessings. She later gains a pet horned owl named Owlowiscious.

In the spin-off movie, My Little Pony: Equestria Girls she transforms into a teenage girl upon entering the human world, though later her element of magic causes her and her counterpart friends to gain some pony-like features. In the sequel Equestria Girls: Rainbow Rocks, Twilight is the temporary lead singer of her rock band, the Rainbooms.

Lauren Faust was inspired to create Twilight Sparkle by her childhood toy G1 pony Twilight. Faust's early design of Twilight shared a similar color scheme and cutie mark with the G1 Twilight, who appears in the pilot episode "Rescue at Midnight Castle". Twilight Sparkle's color scheme was later changed to that of the G3 Earth pony Twilight Twinkle, with a slightly different mane and tail, but Lauren Faust said that Twilight originally had dark blue hair with a light blue stripe; Twilight Sparkle was called "Twilight Twinkle" in early scripts for the show. G1 Twilight teleports by wishing, and Twilight Twinkle likes to watch fireflies; Twilight Sparkle shares aspects from both of these ponies, with her ability to teleport and her occasional stargazing. Though she is much more studious and possesses more powerful magical abilities, she also shares a number of personality traits with the G1 Pegasus Wind Whistler, such as her tendency to rely on logic rather than instincts and her habit of using more advanced and technical terms. She additionally shares some personality traits with the G1 pony named Bright Eyes.

In a 2008 sketch for the series bible, Twilight's cutie mark resembles that of the character Moondancer from earlier My Little Pony generations.

Lauren Faust had planned for Twilight to acquire the power of self-levitation "at some point." Following Faust's departure from the show, Twilight has used this power in the season three episodes The Crystal Empire - Part 2 and Magical Mystery Cure.

As an Alicorn, Princess Twilight is a little taller,her neck is more curved, and her horn is a bit longer than when she was a unicorn.

Twilight Sparkle lives in Canterlot until Princess Celestia sends her to Ponyville. Accompanied by Spike, Twilight checks the town's preparations for the Summer Sun Celebration and befriends the rest of the main characters. The celebration is interrupted when Nightmare Moon, Celestia's nemesis, returns to power and threatens to bring eternal night to Equestria. Twilight and her friends discover the Elements of Harmony and use them to defeat Nightmare Moon. Princess Celestia gives Twilight permission to remain in Ponyville to study the magic of friendship.

Throughout the series, Twilight learns about the trials and rewards of friendship, periodically sending friendship reports to Princess Celestia. On rare occasions, Twilight and her friends work together to defeat powerful villains such as Discord, Queen Chrysalis, King Sombra, and Lord Tirek.

In Magical Mystery Cure, Twilight completes an ancient unfinished magic spell with her deep understanding of friendship. Princess Celestia tells Twilight that she is ready for the next stage of her life, and Twilight is transformed into an Alicorn and crowned a princess.

Princess Twilight Sparkle becomes the ruler of the Friendship Rainbow Kingdom in the season four episode Twilight's Kingdom - Part 2

Cutie mark

Twilight tells the Cutie Mark Crusaders how she got her cutie mark in The Cutie Mark Chronicles. She says that when she was a filly, she studied magic on her own and wanted to attend Celestia's School for Gifted Unicorns. At the entrance exam, Twilight was told to use magic to hatch Spike's egg, but her magic got out of control when she was startled by Rainbow Dash's sonic rainboom. Princess Celestia witnessed Twilight's magical abilities and made Twilight her personal protégé.

Personality

Love of books

In Friendship is Magic, part 1, Twinkleshine says Twilight is more interested in books than friends. Even after Twilight becomes good friends with the rest of the main characters, she continues to read and consult books. For example, she confidently joins a marathon after reading several books about running in Fall Weather Friends. She is also very knowledgeable about Equestria's history, as seen in such episodes as Luna Eclipsed and Testing Testing 1, 2, 3.

Rationality

Twilight tries to be rational in unfamiliar situations. During the investigation in MMMystery on the Friendship Express, Twilight tells Pinkie Pie to stop making wild accusations, and they work together to find clues and solve the mystery.

However, Twilight can lose her cool under stress. In Swarm of the Century, she hysterically suggests building a replica of Ponyville in less than a minute before Princess Celestia can see the damage done by the parasprite infestation.

Twilight tends to be skeptical of unproven claims, such as her friends' belief that Zecora is an evil enchantress in Bridle Gossip, and Pinkie's "Pinkie Sense" in Feeling Pinkie Keen.

Knack for organization

Twilight shows her knack for organization in Winter Wrap Up. When the Winter Wrap Up becomes inefficient and uncoordinated, she organizes the teams and ensures that winter is wrapped up on time. Mayor Mare gives Twilight the official title of "All-Team Organizer". Twilight also uses her organization skills in the episodes Lesson Zero and It's About Time.

Teaching

In the episode Twilight Time, Twilight takes time each week to teach the Cutie Mark Crusaders various skills. She attempts to teachSweetie Belle to use the telekinetic component of her magic, Apple Bloom how to make botanic growth potions and Scootaloo how to strip and reassemble various types of scooter and cycle. Twilight is overjoyed when she thinks the other classmates also want to learn new things, but is disappointed when she finds out that they merely want to spend time with a local celebrity.

Twilight's ability as a teacher is proven in that she succeeds in teaching all three Crusaders the skills she intended to teach them. They all demonstrate a high degree of aptitude at the end of their lessons.

Twilight attempts to teach Rainbow Dash the history of the Wonderbolts, but her methods of study prove futile when Rainbow Dash acts as a class clown in Testing Testing 1, 2, 3.

Magic

Twilight Sparkle is exceptionally talented at magic. In a flashback in The Cutie Mark Chronicles, Princess Celestia tells Twilight that she has never seen a unicorn with so much raw ability.

As talented as Twilight is, her spells occasionally misfire or fail.

• When she casts a spell on the parasprites in Swarm of the Century so they won't eat food, they begin to consume items which aren't food, and subsequently destroy Ponyville.
  
• When she tries to assist with Winter Wrap Up by animating a plow with a "come-to-life" spell, she loses control of it and makes a mess.
  
• In The Return of Harmony Part 1, she tries to reverse Discord's strange effects with a "fail-safe spell", but it fails.
  
• In the episode Magic Duel, she has difficulty performing an age spell, which she says is only for "the highest level unicorns".
  

In the first season, Twilight's horn usually glows white or the same hue as her coat, and the objects she is manipulating glow white, lavender, or pink. When she manipulates multiple objects at once, several other colors are used as well, for example in the gem-finding scene in A Dog and Pony Show. Starting with the second season's third episode, Twilight's magic is uniformly depicted using a pink glow.

Family/Parents

Twilight's parents first appear in The Cutie Mark Chronicles. In a flashback, they excitedly nod their approval when Princess Celestia offers to make Twilight her apprentice. In A Canterlot Wedding - Part 2, they attend Shining Armor's wedding and are moved to tears. They attend Twilight's coronation in Magical Mystery Cure.

Twilight Sparkle's mother resembles the notable G1 pony Twilight in My Little Pony Special, with her hair style similar to Twilight's. Twilight Sparkle's father resembles the G1 pony named Nightlight, but gender-swapped.

Shining Armor

Twilight reveals that she has an older brother, Shining Armor, in A Canterlot Wedding - Part 1. She sings B.B.B.F.F. (Big Brother Best Friend Forever), a song about their close bond and how much she misses him after she moves to Ponyville. Shining Armor, though extremely busy with his duties around the Crystal Empire, still has time for his little sister, whom he calls "Twily".

Princess Cadance

Twilight reveals that Princess Cadance was her foal-sitter when she was a filly. At the end of A Canterlot Wedding - Part 2, Twilight becomes Cadance's sister-in-law when she marries Shining Armor. Twilight enjoys spending time with Cadance as seen in Three's a Crowd when Cadance comes to visit her.

Crowns

For the first three seasons of the show, Twilight possesses a crown containing the element of magic. She receives it in Friendship is Magic, part 2 when she defeats Nightmare Moon. The crown is studded with sapphires and a magenta star-shaped gem shaped like like Twilight's cutie mark.

After Twilight becomes a princess in Magical Mystery Cure, she wears a different crown with the element of magic embedded in it. It is a lighter shade of gold, no longer has sapphires, and rests horizontally, not vertically, on Twilight's head.

Twilight relinquishes her crown when she and her friends restore the Elements of Harmony to the Tree of Harmony in Princess Twilight Sparkle - Part 2. At the Summer Sun Celebration, she wears a new crown, which has the same shade of gold just like and looks completely different from her element of magic crown. It has more of a "classic" crown shape, with each point studded with a small magenta jewel. It becomes her regular crown for the rest of the season, as seen in Trade Ya, Equestria Games, and Twilight's Kingdom - Part 1.