Mary L. Day (born 1836, died after 1883) was an American writer, best known for her 1859 memoir Incidents in the Life of a Blind Girl and its 1878 sequel, The World as I Have Found It.

They lived in a log cabin until her mother died and her widowed father moved away, leaving the five Day children to the care of other families.

She sold copies of Incidents to support herself, traveling the United States with a companion,[4] and making personal appearances.

[1][3] The World as I Have Found It carried an introduction by Charles Deems, a noted Methodist preacher.

[7] Among the stories in the sequel were her impressions of the Solid Muldoon, a "petrified man" hoax in Colorado.