Princess Luna is Princess Celestia's younger sister from "My Little Pony: Friendship is Magic". (In Phase Awesomeness parodies, she's the lover and husband of Agent Classified.)
Princess Luna played Queen Watevra Wa-Nabi in Atypical 2: The Furry Movie (The Lego Movie 2: The Second Part)
She's an alien shapeshifter who eventually wins the heart of Batman.
Princess Luna played Megara in Godzulles
She secretly works for Hades
Princess Luna played Tim the Minion in Awesome Me (alongside Tigress).
She is a tall Minion.
Princess Luna played Princess Kida in Atlantis: The Lost Empire (Twilight'sSpaceStar17's Animal Style)
Princess Luna played Miss Right in The Secret of NIMH (Twilight'sSpaceStar17's Style)
Princess Luna played Dr. Buttocks in Trixie and the Ghostly Adventures
She is a ghost
Princess Luna played J.A.R.V.I.S in The Beak
She is a artificial intelligence
Princess Luna played Karone in Power Ponies In Space and Power Ponies Lost Galaxy
She is Andros' Sister and the 2nd Pink Galaxy Ranger.