Twilight Sparkle is a lavender alicorn pony (previously a unicorn, prior to "Magical Mystery Cure"), with deep purple eyes and a dark indigo mane and tail in a hime cut with a purple and dark pink streak running through them, and is the main protagonist of the series. Her cutie mark is a magenta six-pointed star with five smaller white stars surrounding it. Extremely gifted with magic, she is Princess Celestia's protégée, and once considered study more important than friendship prior to "Friendship is Magic". When in danger from Nightmare Moon's prophecy, Princess Celestia sent her to Ponyville to learn the importance of friendship, which released the Elements of Harmony from her new friends, leading to the defeat, and reforming of Nightmare Moon,[2] later known as Princess Luna.[3] She decides to stay in Ponyville and study friendship with her mentor's blessings, accompanied by her assistant, a baby dragon named Spike.[2 ]

In "Magical Mystery Cure", Twilight accidentally activates an unfinished spell created by historic figure Star Swirl the Bearded, causing her friends' cutie marks to be swapped, thus altering their destinies. After correcting her mistake, Twilight is able to complete the spell, creating new magic in the process. Fulfilling her destiny predicted by Princess Celestia, Twilight is then transformed from a unicorn to an alicorn, and ascends to become a Princess of Equestria alongside Celestia, Princess Luna and Princess Cadence.[4]

Twilight studies extensively and takes an organized, analytical approach to solving problems. She sometimes has insecurities about fitting in, and can often let her fears, insecurities, her desire to impress Princess Celestia, and her logical way of thinking distract her, which sometimes leads to near madness or, in one case, chaos.[5] Unlike other unicorn ponies, Twilight can perform a wide variety of magic, including teleportation, force fields, and telekinesis. She represents the Element of Magic, which takes the form of a tiara. She has an older brother named Shining Armor, the captain of the Canterlot Royal Guard, who marries her former foalsitter Princess Cadance. In "Owl's Well That Ends Well", she gained a pet horned owl named Owlowiscious specifically to defray Spike's workload as assistant.[6] In the movie My Little Pony: Equestria Girls, it is suggested that she might have a crush on Flash Sentry, a pegasus who is a member of the Royal Guard.