Mr. Fitzgibbon

"... in the vegetable garden owned by a farmer named Mr. Fitzgibbon." Mr. Fitzgibbon was a farmer who had two sons (Billy and Paul.) He also had a farm (Which Mrs. Frisby lived on) , plow, tractor etc. and he plowed each year after winter which caused Mrs. Frisby and her family to move to their summer cottage.

The Old Shrew Woman

"... a tiny thing scarcely bigger than a peanut, but with a wit as sharp as her teeth. she lived in a simple hole in the ground a few yards away..." (Pg. 30, 31) Mrs. Frisby had grown to like her and they became friends and talked when they saw each other.

Teresa

"Teresa the oldest..." (Pg.7) was another daughter of Mrs. Frisby who was sister was Cynthia and brothers were Martin and Timothy

Billy Fitzgibbon

"... younger brother Billy, who at age twelve was noisier and had an annoying habit of skimming rocks across the grass at anything that moved." (Pg.34) He was Paul's younger brother and another son of Mr. fitzgibbon. "Mrs. Frisby did not care much for Billy" (Pg.34)

Paul Fitzgibbon

"Paul, at fifteen, was a quiet, hardworking boy, rather clumsy in his movements but strong and careful about his chores." (Pg. 34) he was Mr. Fitzgibbon's son and Billy's older brother.

Jeremy the Crow

Jeremy "The crow who was young indeed in fact only a year old..." (Pg.23) Mrs. Frisby helped Jeremy get   untangled from a piece of shiny string before Dragon got them. in return Jeremy took her home. "... Jeremy was not the brightest of animals... and though he was young, he knew things and places Mrs. Frisby did not..." (Pg. 40)

Mr. Ages

"Mr. Ages was a white mouse who lived across the farm and beyond in a house that was part of a brick wall." He was a mouse who is considered a medicine mouse with lots of medicine.