Grandma Poss is a fictional character from the beloved Australian children's book "Possum Magic," written by Mem Fox. She is a wise and caring possum who uses her magical abilities to protect her granddaughter, Hush. In the story, Grandma Poss creates magical foods that can make Hush invisible to keep her safe from danger. However, as Hush grows older, she wishes to become visible again. The tale follows their adventure to find the right food to restore Hush's visibility, highlighting themes of love, family, and the importance of identity.