Mrs. Mancy is the principal of Westmore Middle School. She has a minor but recurring role in the books.
Role in The Last Straw
In the Valentine's Day Dance, she told every student that the dance would count 20% of their Phys Ed grades and went with Mr. Underwood noting down the marks.
Role in Cabin Fever
Role in The Third Wheel
She is mentioned by Greg when she announced that there is a limit of toilet papers the kids can bring and only 5 are allowed.
- Diary of a Wimpy Kid: The Last Straw (Only physical appearance)
- Diary of a Wimpy Kid: Cabin Fever (Mentioned)
- Diary of a Wimpy Kid: The Third Wheel (Mentioned)
- It's implied that she and Mrs. Heffley are friends, because in the first book of the series, Greg claims that his mother is "really tight" with the principal, and figures that she did some string-pulling to have him put in the advanced reading group (after trying but failing to get put in the easy group).