Monterey Jack, known to friends as Monty, is the oldest of the Rescue Rangers, as it is revealed early on that he was friends with Gadget's father and knew Gadget as a child. He is an Australian mouse, and often uses pseudo-Australian phrases in his speech, such as "Stripe me starkers". Monty comes from a family of travelers and has spent most of his life traveling the world with his sidekick Zipper. He loves to tell stories about his travels, even when the others halt his reminiscing.
He is close friends with Zipper and with Dale, who shares Monty's fun-loving nature, while he considers Gadget akin to a surrogate daughter, due to his friendship with her father. Despite his easy-going nature, he can be quick to anger, which can lead to Monty getting into fights with larger opponents. His bravado vanishes in the face of cats, of which he has an intense fear. At the end of "To the Rescue, Part 5," after Gadget joins the Rescue Rangers, he becomes her guardian.
Monty joins what comes to be known as the Rescue Rangers after his home is destroyed by Fat Cat. This event gives Monty a grudge against the villainous feline that is rarely brought up in later episodes. He is responsible for leading Chip and Dale to Gadget, though he actually intended to meet with her father to obtain transportation.
After Fat Cat is brought to justice, he remains with the squad, serving as the muscle of the group. Being the most traveled of the bunch, he is often responsible for the group's travel arrangements when going long distances. Though a devoted member, he could easily be distracted by his addiction to cheese; upon smelling cheese he goes into a trance-like state known as a "cheese-attack".
Monty and his relatives are all named after types of cheese.
In the episode "Shell Shocked", when a group of hermit crabs reveals that their shells have been taken (essentially, their homes), Chip makes this comment directed to Monty: "How would you feel if you lost your home?" Monty actually did lose his home in "To the Rescue, Part 2".