Butterbean is a loyal, long-haired dachshund who deeply loves her elderly owner. Uncomplicated and guided primarily by her strong sense of smell and simple desires, she initially struggles to comprehend the seriousness of her family's situation. Despite her naivete, her devotion to her household drives her to step out of her comfort zone to help her friends.

Oscar is a mynah bird who functions as the intellectual planner of the household. He derives almost all his knowledge of the human world from watching television, which gives him false confidence in his strategic abilities. Prone to bossiness and dramatic pronouncements, he masks his deep anxiety about the group's survival behind elaborate schemes.

Walt is a cynical and secretive Oriental shorthair cat who favors decisive physical action over Oscar's ponderous planning. She possesses a surprising array of hidden skills, including computer literacy and extensive knowledge of the apartment building's hidden infrastructure. Her tough, sarcastic exterior conceals a fierce loyalty to the other animals.

Madison is a young girl with long black hair hired as the temporary caretaker for the household animals. Fiercely independent, she harbors a major secret about her own living situation, presenting a false facade of stability to the adults around her. Her initial bewilderment at the pets' strange behavior gradually shifts into a relationship of mutual reliance.

The Coin Man is an intimidating, tall resident of a top-floor apartment in the Strathmore building. Known for his icy blue eyes and strong cologne, he exudes a chilling presence that unnerves both humans and animals. His mysterious stash of gold coins makes him the unwitting target of the pets' desperate heist plan.

Marco and Polo are a pair of energetic rats who secretly live in Mrs. Food's office. Often underestimated by the larger pets, they are resourceful and agile, capable of escaping their enclosure whenever they wish. Their small size and ability to squeeze into tight spaces like air vents make them crucial members of the animals' reconnaissance efforts.

Chad is an octopus living secretly on the eighth floor of the apartment building. Pragmatic and highly transactional, he possesses unique physical abilities, such as lock-picking, traveling through plumbing, opening windows, and camouflaging himself against furniture. He requires a strict payment of sardines to participate in the animals' schemes.

Bob is the maintenance man for the Strathmore apartment building. He serves as the primary conduit between the isolated pets and the outside human world, unknowingly providing the animals with critical information about their looming deadline before being sent to an animal shelter.

Mrs. Food is the elderly, affectionate owner of Butterbean, Walt, Oscar, Marco, and Polo. Her sudden hospitalization abruptly strips the pets of their comfortable domestic lives. This medical emergency forces the animals to rely on their own ingenuity to secure a future.

The Number Two Man is a shaggy-haired criminal associate of the Coin Man. He spends his time in the top-floor apartment guarding the duffel bag full of gold coins, presenting a significant physical obstacle to the pets' plans.

Wallace is a former pet rat who now lives as a fugitive in the Strathmore's air vents. Having escaped a stressful domestic situation, he understands the hidden infrastructure of the building and harbors a deep, paralyzing fear of the top-floor residents.