Prunella Deegan is nine years old and a grade above Arthur and his friends, and as a result is somewhat snobbish and condescending towards the younger kids. She brags about winning competitions from last grade and tends to bring it up to Arthur and his friends. She is interested in yoga, fortune telling, and paranormal phenomena. She loves "Henry Skreever", the series' parody of "Harry Potter". She wears a blue dress with a white collar and a purple bow in her hair.