Equestria

A tall, black alicorn mare with a flowing, starry mane and tail that shimmer like the night sky, glowing cyan eyes with slit pupils, and armor plating on her chest and head. Her horn and wings are large and imposing, and her overall presence is both majestic and intimidating.

Nightmare Moon is a complex character embodying jealousy, darkness, and eventual redemption. She is regal, proud, and initially vengeful, but beneath her dark exterior lies a tragic figure longing for acceptance and forgiveness. She commands respect and fear but is ultimately capable of change through friendship and love.

Nightmare Moon is the corrupted form of Princess Luna, consumed by jealousy and darkness due to being overshadowed by her sister Celestia. Once a guardian of the night, Luna's resentment grew as ponies favored the day and Celestia's rule. Her transformation into Nightmare Moon led her to challenge Celestia for control of Equestria, resulting in her banishment to the moon by the Elements of Harmony. She returned centuries later, only to be redeemed and restored to Princess Luna by the power of friendship wielded by Twilight Sparkle and her friends.