While there aren't many details on the character, the studio is seeking an actress who is physically strong and can play between the ages of 25 and 35 for this leading role. The studio has neither confirmed nor denied that the part is, in fact, Wonder Woman, although many talent agencies have been submitting actresses with the belief that it is Diana of Themyscira.
While the agencies don't know that it is Wonder Woman for a fact, there aren't many other female roles in the DC Universe that would be so closely guarded. There is the possibility that the mystery character could be a female villain, although none of the other casting breakdowns have mentioned such a character. Earlier in the month, it was rumored that Bruce Wayne will be getting a love interest in this sequel, and the new casting call does match up with that. Here is what they are looking for in Batman's girlfriend.
Its quite possible that these are both for the same role. Back when this was first rumored, it was speculated that Bruce Wayne's girlfriend was actually going to be revealed as Wonder Woman.
In June, before it was even announced that Batman (Ben Affleck) will be featured in the story, David S. Goyer revealed that the sequel will be the cause of the Justice League, Warner Bros. DC superhero ensemble that is still in development. If that is actually the case, it would make sense to introduce Wonder Woman and other Justice League members in this movie, similar to how Nick Fury was introduced in Iron Man.
Batman v Superman: Dawn of Justice comes to theaters March 25th, 2016 and stars Henry Cavill, Ben Affleck, Amy Adams, Diane Lane, Laurence Fishburne, Gal Gadot, Jesse Eisenberg, Jeremy Irons. The film is directed by Zack Snyder.