I Think I'm A Girl Now?
Men are, you know, men. But there are some male heroes, and evil people, who have female versions with the same exact codename. Here's a nice list of them! This is constantly being added to.
1/2/11 Update: Added a number of different women, and am constantly updating it. :)
3/23/11: Finally, I'm crossing over to the DC universe. I am not as knowledgeable in the DC uni as I am with Marvel so if I get something wrong, just tell me :)
11/24/12: Added some more