The roles for Irina and Renesmee in The Twilight Saga: Breaking Dawn have been cast. Maggie Grace, who formerly played Shannon on Lost, will be starring as Irina.
Irina is the vampire who runs to the Volturi - the Italian government of the vampire world - and rats out Bella and Edward for creating an immortal child. This information is actually false, and Irina must pay the consequences. Grace’s character in the beginning seasons of Lost was easy to dislike, setting a good foundation for her role as Irina in Breaking Dawn.
Nine-year-old Mackenzie Foy, who is a model and an actress, will most likely be playing the role of Renesmee, Edward and Bella’s interesting child. In The Twilight Saga, Renesmee is named after Bella’s mother Renee, and Edwards mother Esme. The child, who has a power unlike any of the other vampires, is quite the disturbing character.
Foy has not actually signed on to star in the movie quite yet, but rumor has it that it’s pretty official.
Source: Entertainment Weekly