Zelda Zenuba Heap, also known as Aunt Zelda, is Silas's aunt and great-aunt to all his children. Formerly the keeper of the Dragon Boat, she passes her responsibility down to Marwick (Wolf Boy). She died in the company of her brothers, Benjamin Heap the tree and Theo Heap, the Storm Petrel. 
Zelda is of medium build, wears a tent-like patchwork dress, has a shock of flyaway grey hair, a wrinkled smiling face, and the bright blue eyes of a White Witch.
It is widely believed that Aunt Zelda has absolutely no sense of taste and cooks dishes mainly consisting of cabbages and eel. The only person (besides Zelda) who can appreciate her cooking is Septimus, who loves her cabbage sandwiches. She has a pet cat called Bert who was turned into a duck so she could enjoy the Marram Marshes. Zelda is often very helpful and does many things for the Heaps. Her house is connected with the palace through the Unstable Potions and Partikular Potions Cupboard that is in both the Queen's Room and Keeper's Cottage. That cupboard also holds the trapdoor that led to the Dragon Boat until the Great Flood, after which it led to the cabbage patch. She's very humble and is an animal lover. The Boggart is a dear friend of hers.