George R.R. Martin recently spoke to TIME magazine about the changes Game of Thrones has made from the books and revealed that he argued against cutting Lady Stoneheart from the show but showrunners David Benioff & Dan Weiss didn’t agree:
“At some points, when David and Dan and I had discussions about what way we should go in, I would always favor sticking with the books, while they would favor making changes. I think one of the biggest ones would probably be when they made the decision not to bring Catelyn Stark back as Lady Stoneheart. That was probably the first major diversion of the show from the books and, you know, I argued against that, and David and Dan made that decision.
In my version of the story, Catelyn Stark is re-imbued with a kind of life and becomes this vengeful wight who galvanizes a group of people around her and is trying to exact her revenge on the riverlands. David and Dan made a decision not to go in that direction in their story, pursuing other threads. But both of them are equally valid, I think, because Catelyn Stark is a fictional character and she doesn’t exist. You can tell either story about her.”