[Senkusha]

This is an interesting concept.  Usually Magical Girls are fierce defenders of love and justice, but what happens when one gets her heart broken?

Are there any anime that specifically feature dark or evilly motivated magical girls?

I know that in Magical Girl Lyrical Nanoha, at least in the beginning, Fate Testarossa appears to be a dark magical girl, but she's just being manipulated by her mother, so I don't count her as dark or evil.  Perhaps her mother, Percia could be considered dark, I mean she does use an electrified whip on Fate and it's revealed later in the series that she does in fact hate Fate with a passion.  But does this neccessarily mean that Percia is indeed evil?

Who else would be considered an evil or dark magical girl?