I STILL stand by my thought, that Raven is the middle character.
The picture in the original post looks so saturated and it isn't increased in size, so you don't notice some of the details...
You can tell that she is wearing a hood. That is not hair, with white highlights. If you look at the white, it folds down onto her shoulders just like a hood would. If you look back and to the left of the white, you will see the back of the hood, which is purple. If you look at the sides of the face, before the white, I have circled the hair coming out of the hood. It is purple. She has pale skin, and dark lipstick.
Sure, it doesn't have the pointy end to the hood, nor does Raven have a white trim to her hood, but these are NRS designs, and her alternate could be her classic look.
As for the character in the top right? I have said that it's Catwoman, maybe in an alt. or something. I swear it looks like her facial structure(jaw, lips, cheeks, eyes seem to be very similar), and it's really hard to tell, but it looks like there's cat ears on top of the head. This is just a pure shot in the dark though, the picture is obviously hard to make out anything for sure given nobody has nailed down anything concrete.
I also don't think the picture neccessarily is relagated to ONLY villains. Nothing says that's the case...the characters could be random, or have some other common link related to the mode you get the achievement from. Sure, all the other characters are villains for sure, but who knows.