Geronimo Stilton has a younger sister and her name is Thea. Thea Stilton has her own series, which you should check out as well. But, I like Geronimo Stiltons books more. G Stilton (Geronimo Stilton) also has his cousin, Trap, and his favourite nephew, Benjamin, in the books too. Now I will tell you about the scariest person: Creepella von Cracklefur with her pet bat Bitwing. Creepella has her own series of books which are good too. The book that I read is "Fright Night." Also G Stilton's books are technically meant for kids 6-12 years old. G Stiltons books came out Febuary 2004. G Stilton is a mouse who lives on mouse island and works as a newspaper writer at The Rodente's Gazette. In some books it shows Geronimo Stilton's girl friend Petunia and her niece Bugsy Wugsy.