Geronimo Stilton is a popular fictional character from the book series of the same name. He is an anthropomorphic mouse and a well-known journalist and editor for The Rodent's Gazette, the most famous newspaper in Mouse Island. Geronimo is a somewhat timid, bookish character, often preferring the quiet of his office or home. However, he frequently finds himself embarking on thrilling adventures, sometimes reluctantly, alongside his family and friends.

As a character, Geronimo is intelligent, good-natured, and resourceful, though prone to nervousness and mishaps. His stories, written in a unique, colorful style with vibrant typography, are filled with humor, puzzles, and life lessons, making them a favorite among younger readers. The series also includes educational elements, often teaching about different cultures, history, and geography.