A pretty woman in her late twenties and the worst Medusa case among the survivors, being the most infected one of them all. Since their encounter she acts in a motherly way towards Tim, the youngest of them being only a little boy. Before becoming infected, Katherine was an alcoholic and was prone to abuse her son Michael, until he was taken away from her and placed in foster care. This events shook her greatly and left her with bitter disgust for herself, prompting her to try to be a true mother for Tim as she wasn't for her son.

Later in the story, the Medusa infection in her completely consumes her body and she turns into stone.