Grandsanta is the 136-year-old father of Malcolm Claus, the father-in-law of Margaret, the grandfather of Arthur and Steve, the previous Santa before Malcolm and the main antagonist turned-deuteragonist of the 2011 film, Arthur Christmas. He dislikes how delivering presents has changed since his time as Santa and believes that he could do a better job the traditional way.
He along with Arthur, Bryony and his pet reindeer travel via his old sleigh Eve (pulled by the great-great-grandchildren of the original eight reindeer) to deliver a bike to a young girl named Gwen after it is forgotten by accident.