Mrs. Frisby and the Rats of NIMH
Mrs. Frisby is the guest of honor in this story and not only because her name comes first in the title. Though the rats also receive top billing, it's really Mrs. Frisby who sets the whole story in motion. She has the problem with her house. She helps set Jeremy free. She goes to see the Owl and then the rats. She offers to deliver the sleeping potion to Dragon. You get the point—without Mrs. Frisby setting the wheels in motion with her tiny feet, this story would be at a standstill.