I don't know why but I LOVE this villain. Thought she's just Sunset's evil part.

First appearance: Equestria Girls

Her appearance, as most people think, I'm sure, is because of her past she had back in Equestria (can be founded in the stories made by fans). Like her parents never cared about her, she wanted to become an alicorn (she could see herself like that through the mirror) and more. Thought in canon she is known as Princess Celestia's former student. What's more interesting - fans were writing in the stories the mirror was possessed by King Sombra. Though there are no evidences in the canon series made by Hasbro.

What I love about her: she's the true villain, she was created from Sunset's negative emotions (stories made by fans), trying to take over the whole Equestria, her being with Flash Sentry (sorry Twilash (Twilight and Flash) fans)

What I hate: her being shipped with Sci-Twi's evil part, Midnight Sparkle, Hasbro not showing the backstory (but thank god we have a fan-made version of it, which was created by Minty Root, named The Fall of Sunset Shimmer: Animated film)

The Fall of Sunset Shimmer (just looking at that I'm thinking still it has My Little Pony Movie parts):

Sunset Shimmer (demon) (defeated):

Her pony version:

She deserved to be here