Thaddeus Mason Harris
|Resting place||Dorchester North Burying Ground|
|Education||Harvard University (1787)|
|Children||Thaddeus William Harris|
|8th Minister of First Parish Church of Dorchester|
|Preceded by||Rev. Moses Everett|
|Succeeded by||Rev. Nathaniel Hall|
Thaddeus Mason Harris (July 7, 1768 – April 3, 1842) was a Harvard librarian, Unitarian minister and author in the early 19th Century. His most noted book was The Natural History of the Bible first published in Boston in 1793.
Harris was named after his maternal grandfather Thaddeus Mason, Harvard University class of 1728 and secretary to Jonathan Belcher. His father William Harris was killed fighting on the colonists' side in the American Revolutionary War. Harris was born in Charlestown, Massachusetts, but after his father's death he was sent to live on a farm in Sterling, Massachusetts. Harris went on to study at Harvard from which he graduated in 1787. After graduation from Harvard, he spent a year as a school teacher in Worcester, Massachusetts. At the end of his teaching stint in Worcester, Harris was offered an appointment as secretary to George Washington, but contracted small-pox, and his recovery time prevented him from taking the post. He became the librarian of Harvard in 1791 and then was appointed the minister of the First Parish Church of Dorchester on Meeting House Hill in Dorchester, Massachusetts, in 1793. He was elected a Fellow of the American Academy of Arts and Sciences in 1806. Harris was also a founding member of the American Antiquarian Society in 1812, and served as corresponding secretary from 1812–1831, and as secretary of foreign correspondence from 1831–1832. The Antiquarian Society holds original copies of a significant number of Harris's published works, as well as some manuscript items from his personal papers.
Harris's son Thaddeus William Harris would also serve as a librarian at Harvard and be one of the leading American naturalists in the first half of the 19th century.
His publications include:
- Journal of a Tour into the Territory Northwest of the Alleghany Mountains (1805)
- The Natural History of the Bible (1820)
- Biographical Memorials of James Oglethorpe (1841)
- Alfred Claghorn Potter, Charles Knowles Bolton (1897), The Librarians of Harvard College 1667-1877, Cambridge, Mass.: Library of Harvard University, OL 7223959M
- "Book of Members, 1780–2010: Chapter H" (PDF). American Academy of Arts and Sciences. Retrieved August 7, 2014.
- American Antiquarian Society Members Directory
- Dunbar, B. (1987). Members and Officers of the American Antiquarian Society. Worcester: American Antiquarian Society.
-  Catalog search for Thaddeus Mason Harris in the American Antiquarian Society online catalong
-  Thaddeus Mason Harris papers at the American Antiquarian Society
- Seaburg 2000
- Seaburg, Alan (2000). Harris, Thaddeus Mason (1768-1842). American National Biography Online. Oxford University Press. doi:10.1093/anb/9780198606697.article.0800631.