Monty

Monty is a brown mouse that appeared in the story "Rats!".

History
Monty moved into the Burnses' house, chewed a hole in the cereal box, and pooped in the cupboard. When Bertie noticed the hole in the cereal box, Mrs Burns investigated and found Monty's droppings in the cupboard. Bertie's parents wanted to get rid of Monty, even kill him, but Bertie wanted to keep him for a pet and housetrain him. When Bertie's father set a fatal mousetrap, Bertie replaced it with a safe trap and caught Monty.

When his mother discovered Monty, she didn't allow Bertie to keep him but he took him to school and showed Darren and Eugene. Monty then escaped and ran up Miss Boot's skirt, who freaked out because she's scared of rats and thought he was a rat. It's unknown what happened to him after that.