Mary Anne Spier is a fictional character from the popular children's book series The Baby-Sitters Club, created by Ann M. Martin. She is known for her responsible and caring nature, often taking on the role of the group's planner and organizer. Mary Anne is characterized by her love for reading and her close relationship with her father, which influences her personality and decisions. In the series, Mary Anne is a member of the baby-sitting club alongside her friends, including Kristy Thomas and Claudia Kishi. Her character often faces challenges related to her shyness and desire to assert herself, making her relatable to many young readers.