Perhaps some people recognized Zoe Bell in Django Unchained from her eyes alone, but I didn't know it was her until I saw her name in the credits. Playing the mysterious masked woman, we never get to know anything about her character, but E! caught up with her recently and got a few quotes as to just what exactly was up with her and that mask.
"There was backstory and there was to be a fight sequence..." Bell said, "But I guess when you're getting such brilliant shit with Leo [Dicaprio] and Jamie [Foxx] and Christoph [Waltz], you just keep shooting and time kind of got crunchy."
So unfortunately it sounds like her sequences weren't even shot, so don't go expecting anything more on a possible extended cut. And as for the mask, "Part of my face was missing."
Costume designer Sharen Davis alluded to this previously in her interview with Vanity Fair, which read: "That leaves some unexplained characters, like that of the beautiful lady outlaw whose face is half-covered throughout the film. (The idea there, says Davis, is that the character would drop the bandana to reveal an absent jaw.)"
It would seem neither the reveal or her fight were ever filmed and those that have read the script (download it here) don't remember her character at all. So what may have been seems to be locked inside Tarantino's head... for now.
I know some will probably say they'd like to see more of her character, but I think the mystery makes it all the more intriguing.