[Name] Wilhelmina Robinson [Nickname] Bill [Appeared in Form] Forms 3–6 [Note] 
Willful and head-strong, Wilhelmina is a fan of horses. Arrives in third form. Is a Tomboy, an only girl with seven brothers, who adores her horse, Thunder. She also insists on being called Bill.Rude to teachers, disobedient,she can't stay out of trouble for the love of her horse, Thunder. Becomes a close friend of Miss Peters after the teacher helps save Thunder from serious colic. Becomes friends with Clarissa Carter, also a good rider and horse enthusiast.