Astrid, The Witch of Mirrors. Her nature is envy. She will resent anything beatiful or that reminds her of her past life. She strips anyone who wanders in her barrier of their posessions... including their bodies.

Here's a tricky one, who takes posession of bodies of magical girls from beyond a mirror. Definitely a nasty bastard.

Edit:Since I'm outta the loop I'm kinda bored here.