Tail for Princess Luna from MLP:FiM, in her Season 1 incarnation.
I think this long variant is a little nicer than the short alternative, but be aware that it intersects the ground line when the character is pushed down. It's not that noticeable most of the time.
This is another hack on @dantethedarkprince 's MLP tails. with my own SVG designs in Inkscape this time. All repacked with lovingly awful Python/swfmill code.