Mary Day
Mary Day may refer to:
People
- Mary Day , founder of The Washington Ballet
- Mary Anna Day, American botanist and librarian
- Mary E. Day, in the 2005 Supreme Court opinion Varian v. Delfino
- Mary L. Day, American memoirist
- Mary Gage Day, American physician and medical writer
- Mary Louise Day, teenage girl who mysteriously disappeared from her home
Days
- Marian feast days