Algernon

The mouse who was the first subject of the surgery which raised Charlie's intelligence. Charlie forms a close emotional bond with the mouse, who is the only other creature to have had its intelligence artificially raised. Its experiences, and fate, parallel Charlie's.

Fanny Birden

An older woman who works at the bakery with Charlie and who is the only employee who does not sign a petition demanding Charlie's resignation after his IQ is raised. She compares the change in Charlie's intelligence to Adam and Eve eating of the fruit of the Tree of Knowledge and wishes that Charlie "could go back to being the good simple man you was before."

Joe Carp

One of Charlie's coworkers at the bakery. and, with Frank Reilly, one of his chief tormentors.

Mr. Arthur Donner

The owner of the bakery where Charlie works, Mr. Donner is a friend of Charlie's Uncle Herman...