It was recently announced that Holly Hunter would be joining the cast of Zack Snyder's Batman Vs. Superman. There was no information on the character she would be playing, other than that it would be a new character created for the movie.
Latino Review may have been able to shed some light on who she will be playing in the movie. They think that the actress will be playing Leslie Thompkins, or "a Leslie Thompkins replacement character."
The site goes on to explain that Leslie is "a doctor who went to medical school with Bruce’s dad before he was murdered and in some versions of the Batman mythos, comforted young Bruce the very night of. Think of her like a female Alfred, almost."
The character did appear in Batman: The Animated Series. She knew Bruce Wayne was Batman and would even treat Bruce for medical injuries. Technically, she and Alfred are like surrogate parents to Bruce.
This is just a rumor for now, but it makes sense, and would be cool if it was true. Jeremy Irons and Holly Hunter working together to help Batman would be really great.