I've got a long dark purple wig I used for cosplaying Rarity from My Little Pony, and I still want to put to use! Who do you know that has long dark purple curly hair?

Sorry I don't know of any characters with dark purple curly hair. :l

You could straighten it, it would give you some mais options.

Cornelia Li Britannia from Code Geass has wavy/curly hair.
Yoruichi from Bleach has long dark purple hair.
Ririchiyo Shirakiin from Inu x Boku SS has long straight dark purple hair with bangs.

Hope I was able to help some. :)

The only character I can think of that is even close is Blair from Soul Eater

Gakupo Kamui (Vocaloid)