Monterey Jack, or "Monty" to his friends, is the tetartagonist of the show. He is an adventure-loving Australian mouse who spent years traveling the world before a chance meeting with Chip and Dale during their first case. Monty has an overpowering addiction to cheese, and the sight or smell of cheese causes him to be almost hypnotically drawn to it. This has gotten him and his friends into trouble on more than one occasion.
Stronger and larger than the others, Monty can be quick to anger if he, or his friends, have been offended. This trait sometimes leaves him ready to do battle with a much larger opponent, and the others having to calm him down.
Monty loves to tell stories of his travels, and he often uses colorful "pseudo-Australianisms" while talking, such as "Stripe me starkers."
Monty is most frequently found in the company of either Zipper or Dale, whose fun-loving nature matches his own. He also seems to consider his fellow mouse Gadget to be something of a surrogate daughter, most likely due to his long friendship with her late father.
After Fat Cat destroyed his home, Monty and his sidekick Zipper decided to join Chip and Dale in their detective work.
- Monterey Jack is the only Rescue Ranger known to have two identified living parents: Cheddarhead Charlie and Camembert Kate, who are also travelers.