Geronimo Stilton is the titular main character in the popular Italian book and TV series of the same name. He is the editor-in-chief of the Rodents Gazette, the most famous newspaper in New Mouse Island. He loves his nephew, Benjamin Stilton, and his sister Thea Stilton and Trap Stilton.
Geronimo is a quiet mouse who loves to read, especially to his nephew Benjamin. He hates going on adventures, but is always tricked into going on them by his family. He is also in love with a mouse named Petunia Pretty Paws but is afraid to tell her. Petunia has a nephew, Bugsy Wugsy, who is adventurous and annoying. While he loves Petunia, there is a gothic, creepy mouse, Creepella von Cacklefur, who is lovestruck with Geronimo and wont leave him alone. Despite this, Geronimo admits to finding Creepella fascinating.
Geronimo has a rival, named Sally Ratmousen, who hates Geronimo with a passion. She runs a different newspaper company, the Daily Rat, and she tries to prove it is better than the Rodents Gazette. Sally has a cousin known as The Shadow, who is one of New Mouse City's most notorious thieves. Geronimo occasionally comes across The Shadow though she usually escapes. So far, he has only caught The Shadow once, but she later escaped.