The character known as Hello Kitty is officially named Kitty White. She was created by the Japanese company Sanrio and first appeared in 1974. Her backstory establishes her as a bright and kind-hearted anthropomorphic cat who lives in the suburbs of London, England, with her family. Her birthday is November 1. In a unique description of her physical dimensions, her height is said to be the equivalent of five apples tall, and her weight is the equivalent of three apples.

Kitty White is depicted as a cheerful and warm individual who is known for her friendly and helpful nature. She is very close with her family, particularly her twin sister, Mimmy. While Kitty is characterized as outgoing, her sister Mimmy is often portrayed as more shy and girly. The most recognizable way to tell the two apart is by the color and placement of their bows: Kitty wears a red bow on her left ear, while Mimmy wears a yellow bow on her right ear. Her personality is generally presented as optimistic, and she consistently approaches situations with a gentle heart and a desire to help others. Her hobbies include baking cookies, playing the piano, and collecting cute trinkets. She especially loves the apple pie her mother makes, and her favorite subjects in school are English, music, and art.

One of the most notable design features of Kitty White is that she has no visible mouth. Sanrio has explained that she does not have a mouth so that people can project their own feelings onto her, allowing them to be happy or sad together with the character. Another explanation is that she speaks from the heart, acting as an ambassador to the world who is not bound to any particular language. Within her fictional universe, she has a wide network of relationships. Her father is named George, her mother is Mary, and she has grandparents named Anthony and Margaret. She also has a boyfriend named Dear Daniel, who is her childhood friend. Her pet cat is a white Persian named Charmmy Kitty.

In terms of her role, Kitty White is the central figure of a media franchise that includes numerous animated series, films, and other productions. In these stories, she often finds herself in everyday adventures with her diverse group of friends, which includes characters like the rabbit My Melody and the penguin Badtz-Maru. The narratives typically focus on themes of friendship, kindness, and problem-solving, where Kitty acts as a supportive and unifying presence among her peers. For example, in the web series Hello Kitty and Friends Supercute Adventures, she is shown offering comfort and encouragement to friends who are feeling sad or stressed, helping to lift their spirits with simple acts of kindness. Over the decades, her character has seen development primarily through these different series and merchandise themes, which are regularly updated by lead designer Yuko Yamaguchi to follow current trends in fashion, movies, and television, keeping the character relevant while maintaining her core identity as a symbol of friendship. Her notable abilities are not supernatural but rather social and emotional; her primary skill is fostering communication and goodwill, and she is described as being good at baking and playing the piano.