Molly Weasley's mother

Mrs. Prewett
Mrs. Prewett is the mother of Molly Weasley, Gideon Prewett and Fabian Prewett. She has not appeared in any of the books as she is deceased before the books begin and not even her first name is given. She is the maternal grandmother of Bill, Charlie, Percy, Fred, George, Ron and Ginny Weasley and she is also the mother in law of Arthur Weasley.