Dark Luna, the dark half of Luna the cat from the future. She is Sailordarkcosmos' guardian and advisor. Actually the cat should have grey fur at her temples but I forgot to put it in. Oops. The tiara she wears is a small replica of Neo-Queen Serenity's tiara.
The original image for this picture came from Kaze no Ohimesama's :|: Anime Coloring Album (the Sailormoon section) which has since closed down. It was modified, then colored by me.