Luna

Princess Luna is an Alicorn mare and the younger sister of Princess Celestia.

Appearance
Luna is taller and thinner than most ponies, with a square face, kind of like her sister but shorter. She has navy-blue fur (with a black blotch on her flank) and a sparkly, navy-blue mane and tail, which seem to move like Celestia's. Her eyes are blue and she seems to wear blue eyeshadow. She wears a black crown, lilac shoes, and a black necklace with her cutie mark on it; her cutie mark being a half-eclipsed moon.

Personality
Ever since she stopped being Nightmare Moon, Luna has been very kind and wise, often advising ponies. She has the ability to appear in other ponies' dreams and communicate to them via a sort of "dream telepathy". She also raises the moon.

Earlier Life
When they were young fillies, Celestia and Luna were hired to raise the sun and the moon respectively, thus earning their cutie marks. This went on until Luna grew jealous of Celestia because the ponies were active during the day but slept during "her beautiful" night. This led her to transform into an evil alter-ego called Nightmare Moon who wanted to fuck ponies. Celestia tried to reason with her sister but it didn't work, so she used the Elements of Harmony to banish Nightmare Moon in the moon. This went on for a thousand years, until Nightmare Moon broke free, starting the events of "Friendship is Magic".

Before she became Nightmare Moon, she and Celestia took the Elements of Harmony from the Tree of Harmony for the first time and used these to turn Discord into stone.

Trivia

 * Up until "Luna Eclipsed", Luna believed it was still traditional to use the "Royal Canterlot Voice". This voice included being very loud, speaking in the royal "we" and using words like "thy" and "Hear ye".
 * When she first came back, her hair was a paler blue and was less wavy and sparkly.