Nicknamed "Squirrel," Cyril is the oldest of the five siblings. He acts as a resourceful leader when the children face magical complications, taking charge of difficult situations. Though his status as the eldest makes him somewhat bossy, he strictly values honor and despises deceit. He skillfully uses double-speak to tell adults the truth without exposing their magical secrets.

Called "Bobs," Robert is the middle boy of the family. He possesses a quick temper and frequently quarrels with his older brother. His thoughtless nature leads to careless wishes that endanger his younger brother and cause chaos for the group. Despite these faults, he demonstrates physical bravery when facing the literal consequences of their magic.

Nicknamed "Panther," Anthea acts as the peacemaker among her siblings. She possesses a kind heart and consistently shows tact, especially when flattering the grouchy Sand-fairy to secure wishes. She is particularly devoted to the baby and frequently formulates clever plans to rescue the group from magical mishaps.

Also known as "Pussy," Jane is a deeply hopeful and affectionate younger sister. She maintains strict honesty, often blurting out the truth even when it threatens to expose their magical secrets to adults. She possesses a sensitive nature and frequently bursts into tears when overwhelmed by their adventures.

The Lamb (whose given name is Hilary) is the two-year-old baby brother of the siblings. As a spoiled toddler, his bothersome behavior frequently annoys the older children. He unwittingly becomes the target of careless wishes, forcing his older siblings into frantic rescue missions to protect him from bizarre magical consequences.

The Psammead, or Sand-fairy, is an ancient creature resembling a fat spider with snail-like eyes and bat-like ears. Unearthed in a gravel pit, it possesses the power to grant one wish a day until sunset. Grouchy, vain, and highly critical of modern times, it frequently scolds the children for their lack of foresight while begrudgingly fulfilling their requests.

Martha serves as the children's unimaginative but dedicated nursemaid. Left in charge when the parents depart, she enforces ordinary household rules. Because the children wish for servants to remain unaware of the magic, she continues her domestic duties in hilarious ignorance of the supernatural chaos surrounding her.

The mother of the five children leaves for a trip shortly after the family arrives at the White House. She represents the ordinary adult world, forcing the children to carefully conceal their magical activities to avoid alarming her when she returns.

A wealthy local woman who travels in a carriage. She becomes swept up in the magical consequences of the children's wishes when she develops an unnatural, overwhelming desire to take the baby away from his siblings.

A local gamekeeper who becomes amiably involved with the children after discovering them stranded during an adventure. He proves helpful to the family, safely transporting them home and developing a steady interest in their nursemaid.

A local youth who fails to understand the children's pretend games. Ignorant of fair play, he reacts aggressively to their play-acting, physically beating Robert and prompting a retaliatory magical wish.