A hard-working young boy who tends to his family's newsstand and becomes Chester's gentle caretaker and good friend.

A sociable and excitable city mouse who befriends Chester and enjoys scrounging and eavesdropping, living in a drainpipe with his friend Harry.

A huge tiger cat with gray-green eyes and black stripes, who is best friends with Tucker Mouse and appreciates music.

Mario's father, a kind and mild-mannered man who enjoys Italian opera and works hard to make the family newsstand a success.

Mario's mother, a practical and strong-willed woman who is concerned about finances and the effects of Chester's presence on their livelihood.

A music teacher and the Bellini family's best customer, who appreciates Chester's music and helps introduce him to fame.

An elderly Chinese shopkeeper with a cheerful demeanor, who befriends Mario and Chester and shares cultural stories with them.