The girl in The Cat in the Hat is named Sally. She is the unnamed boy narrator’s sister, and the two children are home together on a cold, rainy day while their mother is away.
Sally and her brother are sitting indoors and looking out the window when the Cat in the Hat arrives. The Cat entertains them with tricks, then brings in Thing One and Thing Two, creating an increasingly chaotic scene. The children also interact with the Fish, who warns them that the Cat’s behavior is dangerous and disruptive.
Readers sometimes remember only the narrator because the boy tells the story in the first person and is never given a name in the original book. Sally, however, is identified by name. Later adaptations add different details: the 2003 film calls her Sally Walden, while the original book presents her simply as Sally, the narrator’s sister.