*Sunset Shimmer is a female unicorn pony-turned-human student of Canterlot High School and a main character in the Equestria Girls franchise. She is the reformed main antagonist of My Little Pony Equestria Girls and the leader of the Equestria Girls.

Throughout the first film, Sunset Shimmer is shown to be self-absorbed, condescending, manipulative, and dishonest. She frequently insults and belittles others and thinks little of it. According to human Fluttershy, Sunset makes life miserable for "anyone who stands in her way". As a result, most of the Canterlot High School student body is afraid of her. She is also not above making threats and blackmail in order to realize her goals.

When Sunset puts on the element of magic, she transforms into a demonic visage of herself. While in this form, she becomes more ruthless, going so far as attempting to dispose of Twilight. After she is defeated, Sunset Shimmer becomes immediately repentant and apologizes for everything she's done, appearing to renounce her prior dishonest and unkind ways.

In the second film, Sunset Shimmer has completely discarded her old self and starts believing in friendship, being kind toward others and befriending former enemies. She is also deeply repentant for what she did in the first film's climax, referring to her transformed self as a "raging she-demon". However, she suffers from a lack of confidence, keeping silent in situations she feels it isn't her place to speak up and falling prey to the Dazzlings' taunting. During the final battle, she finally overcomes her insecurities and joins the Rainbooms in defeating the Dazzlings, gaining a half-pony form in the process. By the end of Rainbow Rocks, Sunset starts writing friendship reports to Princess Twilight using the book she once used to communicate with Princess Celestia.

By the third film, while Sunset has managed to fully integrate herself into the group and take mentions of what she did in the past with good humor, she also harbors a fear of losing her school's newly gained trust, and she becomes deeply depressed when she believes she has let them down, despite their assurances. She also becomes increasingly irritated and stressed by her struggles to understand how magic works in the human world, briefly snapping at her friends at one point. When Sci-Twi endangers her friends, Sunset's anger explodes as she berates Twilight for meddling with forces she doesn't understand, taking her own frustrations and self-doubt out on her. However, she immediately regrets her harsh words and reaches out to Twilight in friendship by the end of the film.

In the My Little Pony: Equestria Girls Holiday Special comic, Sunset Shimmer displays a forgiving and compassionate side when she forgives the Crusaders for framing her as the rumormonger "Anon-a-Miss".

In Sunset Shimmer's Time to Shine, Sunset displays a considerable level of intelligence, being ahead of her friends and classmates in school and smart enough to develop various computer applications. Her affinity for science and research is also seen in The Science of Magic, where she explains she prefers a hands-on approach to studying magic over "studying ancient books".

Having spent few years in the human world and after her reformation, Sunset has grown fond of it, having taken several human habits, such as playing video games and posting in social media, and referring to it as "her world". She also has grown used to her human body, to the point of having to re-adapt to her pony form whenever she goes back to Equestria.

In her human form, her skin is light amber, and her hair having the same colors as her mane and tail but as wavey as it is. Since The Legend of Everfree, she wears a neon orange necklace with a red geode pendant and her pony counterpart's cutie mark on it around her neck.

In the first two movies, she wears a black leather sweatshirt over a magenta shirt with her pony counterpart's cutie mark, an orange skirt with magenta and yellow lines, and black V-shaped knee-high boots with magenta flame designs.*