Hermione Granger is one of Harry's best friends in the Harry Potter book and movie series. Hermione was born to a family of muggles (two Dentists) and is constantly teased for being a mudblood. Hermoine is extremely booksmart and is extremely valuable to Harry as he goes on his adventures.
Ron: Hey, Hermione... you're a girl. Hermione: Oh, well spotted. Ron: [miming a dance] Come with one of us? [Snape swiftly hits Ron on the head with a notebook] Ron: Ow!