Just as most everyone figured, Holly Marie Combs has not been cast as Catelyn in the Game of Thrones pilot. This comes straight from Benioff and Weiss themselves, courtesy of the Westeros forums. In responding to a poster who stated they hoped that the casting of Holly Marie Combs wasn’t true, David & Dan say this:
Don’t worry, it’s not.
Winter Is Coming: No big surprise here. But nice to get official confirmation.