Princess Celestia is an Alicorn pony, the co-ruler of Equestria alongside her younger sister Princess Luna, and the adoptive aunt of Princess Cadance. In addition to her responsibility of raising the sun, she has also been the teacher of Twilight Sparkle and Sunset Shimmer at different periods in time, often addressing Twilight as "my faithful student" while mentoring her. She has a pet phoenix named Philomena. She is called Nightmare Star in some merchandise.