Appletwirl is Applejack's sister, and part of the Apple family. She is the only pony who is a unicorn pony in the Apple family. She's just like Twilight Sparkle, and they become good friends. She is voiced by Kat Mertins. Her voice is similar to Applejack's only it was lower pitched and a little bit faster.
She has a braided mane, and wears a cowgirl hat like Applejack, but with different color as in Apple Green. She also has a horn. Her skin is bright yellow.
Appletwirl mentioned her cutie mark on "Lost and Found". She mentioned it to Caramel Apple. Appletwirl says that she earned it when her little sister Apple Bloom was about to fall from a tense cliff. Luckily she saved her using her magic from her horn. Then her cutie mark appeared. It was a shiny golden apple.
Yee haw! Now, Applejack, be careful! (Lost and Found)
My knees are wobbling. (Lost and Found)
And WHO EVEN ARE YOU, PARTNER?! (To Discord in Elements of Harmony vs. Elements of Evil Part 1)
She's the most beautiful pony I've ever seen. (Referring to Applejack in Elements of Harmony vs. Elements of Evil Part 2)