Billy Sparks’ sister, Missy, was not a character on “Young Sheldon.” Billy is a recurring character, but the show does not focus on his family or siblings.
In the series “Young Sheldon,” Billy Sparks is depicted as a neighbor of the Cooper family. He is often seen interacting with Sheldon and his family, but the show does not delve into his family life in great detail. As such, there is no storyline or character development surrounding a sister for Billy Sparks. The show primarily focuses on Sheldon’s immediate family and his experiences as a child prodigy, with other characters like Billy providing additional context and interactions in the young genius’s life. It’s important to note that “Young Sheldon” is a spin-off prequel to “The Big Bang Theory,” and while it includes many references and characters that fans of the original series would recognize, it does not explore the extended family of every supporting character.