Lettie Hatter is a supporting character in the anime adaptation of Howl's Moving Castle, produced by Studio Ghibli and directed by Hayao Miyazaki. She is the younger sister of the protagonist, Sophie Hatter, and works as a chocolate sales clerk at Cesari's, a large and popular café in the town of Market Chipping. In the film, Lettie is depicted with strawberry blonde hair, blue eyes, light blue eye shadow, and salmon-colored lipstick, and she wears a light pink dress with a darker salmon apron and large red spherical earrings. Her demeanor is cheerful and outgoing, and she is well-liked by the café's patrons, reflecting a warm and sociable nature.

In the context of the story, Lettie's role is relatively brief but meaningful. She is shown interacting with Sophie when Sophie visits the café, and she later appears when the wizard Howl visits Cesari's. Lettie is also present in a scene where she watches the departing airships, providing a glimpse of civilian life during the ongoing war. Beyond her appearances, the film suggests a close bond between the sisters; Lettie is visibly concerned for Sophie's well-being and happiness. When Sophie asks whether she should stay in the hat shop, Lettie questions whether that is truly what Sophie wants, gently encouraging her to consider a different path. This moment hints at Lettie's perceptiveness and her desire for Sophie to find fulfillment, even though Lettie herself seems content with her own life at the café. She does not possess any magical abilities or play a direct role in the central conflict, instead functioning as a grounded, everyday figure who represents Sophie's past life and family ties. Her personality is characterized by a sense of practicality, warmth, and a quiet strength that contrasts with Sophie's initial self-doubt. Lettie's limited screen time means her personal ambitions and deeper motivations are not explored in the film adaptation, but her presence reinforces the theme of familial love and the importance of finding one's own path.