from The American Heritage® Dictionary of the English Language, 4th Edition
- Day, Benjamin Henry 1810-1889. American printer and journalist who founded the first penny newspaper, the New York Sun (1833). His son Benjamin (1838-1916) invented the Ben Day process for shading printed illustrations.
- Day, Clarence Shepard, Jr. 1874-1935. American writer best known for his autobiographical Life with Father (1935) and Life with Mother (published 1937).
- Day, Dorothy 1897-1980. American journalist and reformer who cofounded the Catholic Worker in 1933 to promote pacifism and social justice.
- Day, Stephen 1594?-1668. English-born colonist who was the first printer in New England. His Bay Psalm Book appeared in 1640.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- proper n. An Irish surname anglicised from Ó Deághaidh ("descendant of a person named Good Luck").
- proper n. A Mbum-Day language of Chad.
This surname has multiple origins. Besides the ones listed below, Norman origin has also been suggested from De Haie", or "a corruption of the Normandy French D'Ossone, from the town of Ossone, in Normandy".  (Wiktionary)