Princess Luna

Princess Luna was shown too reappear yet again in the Seven Seals once again as Nightmare Moon. She is an Alicorn pony, the younger sister of Princess Celestia, and the Co-ruler of Equestria, and Rivera's formal Wife.

Personality
Thanks to Pinkie Pie's insight, Twilight Sparkle realizes that because of the Luna having funholiday, Pinkie Pie and her entourage actually want to be frightened, so she arranges for Luna to purposefully scare them. Luna appears as Nightmare Moon, scares the ponies, and bares fangs. After the ponies run away in fright, she changes back to her usual appearance and spits out the false fangs she was wearing, confused as to why Twilight wanted her to do that. Then Pipsqueak approaches Luna on behalf of the children and asks her to come back and scare them again next year, even though she canceled Nightmare Night. Luna begins to understand and reinstates Nightmare Night, at which point Pipsqueak declares her his "favorite princess ever" and hugs her leg.

The princess manages to relinquish the use of her royal Canterlot voice, and in the epilogue she plays a variety of games with the villagers, accepts the foals' candy, and frightens Rainbow Dash by firing a bolt of lightning behind her, a trick that Rainbow Dash had been playing on other ponies over the course of the night.