Animated version voiced by: Brian DrummondThe editor in chief of The Rodentís Gazette, the most famous daily newspaper on Mouse Island, but his true passion is writing books, which all become bestsellers. He enjoys reading books, listening to classical music, and playing golf; he even collects antique, 18th century cheese rinds, of all things! He adores his work and his family, but he hates to travel, because he gets airsick, seasick and carsick. Nonetheless, he often gets involved by Thea and his relatives and friends in extreme situations and adventures all around the world.
Tropes associated with Geronimo:
- Crouching Moron, Hidden Badass: If he's pushed far enough.
- The Drag-Along: He hates to travel, and often resists being sent far afield, for all the good it does him.
- Meaningful Name: Surname plays on mice's purported love for cheese.
- The Name Is Bond, James Bond: Geronimo introduces himself this way at least once per book. One book is even titled My Name is Stilton, Geronimo Stilton.
- Only Sane Mouse: He comes across as this; both as a foil to Trap's Cloud Cuckoolander tendencies and as a point from which the comedy is milked for all it's worth.
- Sharp Dressed Mouse
- Weirdness Magnet: Geronimo gets into strange and bizarre situations no matter where he goes, and staying at home doesn't keep him safe from it either.
Animated version voiced by: Sarah EdmondsonGeronimo's youngest sister, a rodent with a professionally successful career, and unrepentant heart-breaker in her private life. A skilled photographer continuously in search of her latest scoop, Thea is ready to leave to exciting adventure at the mere drop of a word, and punctually returns with sensational articles and photos. She rides a motorcycle, flies a plane, loves racing cars, is a certified parachute jumper, holds a black belt in karate, and teaches survival courses. Thea can also be frivolous and teasingly spiteful, and loves the latest fashions. She has her own series about her friends at Mouseford Academy. She is a special correspondent for The Rodent's Gazette.
Tropes associated with Thea:
- Action Girl: Unfortunately, she's always the first to suffer The Worf Effect, though not to the extent of being rendered into fauxhood.
- Screw the Rules, I'm Beautiful!: She often uses her feminine wiles in this manner. But she doesn't get to do this in the Animated Adaptation, where she's portrayed as a little tomboyish. She even hates fashion and anything that has to do with making girls look pretty, judging from the episode "Top Model Thea".
Animated version voiced by: Richard Ian CoxGeronimo's annoying cousin. He is always eating all of Geronimo's food, hence his largely rounded appearance. Trap is called obnoxious in most of the Geronimo Stilton books but appears as a very interesting character. Trap believes that he is a good cook, but Geronimo thinks otherwise. Trap is loud and obnoxious, and he always wants money. He lets Geronimo do all the work. Trap always does pranks on Geronimo, and is always signing Geronimo up for things that he does not like to do. He also has friends all over New Mouse City. He owns a shop called Cheap Junk for Less.
Tropes associated with Trap:
- Innocently Insensitive: Whenever Geronimo is having a problem, Trap will always say something that reminds him of the problem and makes him feel worse. However, Trap isn't being malicious; he either doesn't realize the effect of his words, or he thinks he's helping.
- Large Ham: And how.
Animated version voiced by: Erin MathewsGeronimo's favorite, 9-year-old (12 in the animated series) nephew. Benjamin is a sweet, polite boy. His teacher at school is Miss Angel Paws, and his best friends are Sakura and Oliver. He has a great curiosity and is surprisingly enterprising. He is always very busy jotting notes on his notepad during other adventures. His dream is to work alongside with his uncle as a successful journalist in the future. Benjamin is Geronimo's favorite rodent and is a needed character in the books. Whenever Geronimo doesn't agree about anything, only Benjamin's pleading look is needed to make him agree.
Tropes associated with Benjamin:
- Adorably Precocious Child: Despite being a grade school student and short of being on the actual payroll, he's treated almost like a part of The Rodent Gazette's staff due to his expertise and considerably mature personality but not to the extent of coming across as a miniature adult.
- Child Prodigy: He is undeniably smart for his age.
- Cross-Dressing Voices: In the Animated Adaptation.