Mary has purplish-black hair twisted in a distinctive style like a witch's hat, a plump physique, and dark brown eyes. She wears a red vest that has several metal rings attached to the bottom over an orange shirt, a plaid skirt underneath a reddish-purple apron, and a red matching cloak.

Mary is Winifred's right-hand witch, always trying her best to appease Winnie and calm her rages. As such, she has a slight rivalry with her sister Sarah.