John Dawson Gilmary Shea (July 22, 1824 in New York City – February 22, 1892 in Elizabeth, New Jersey) was a writer, editor, and historian of American history in general and American Roman Catholic history specifically. He was also a leading authority on aboriginal native Americans in the United States.
John Dawson Shea was born in New York City to James Shea, an Irish immigrant and school principal, and Mary Ann (Flannigan) Shea. His early studies were at the grammar school of Columbia College, where his father was principal. At an early age he became a clerk in a Spanish merchant's office, where he learned to read and write Spanish fluently. He studied law, and was admitted to the bar in 1846. From 1847 until 1852 he was a member of the Society of Jesus; during this time he added his middle name of Gilmary ("servant of Mary"). He studied at St. John's College (now Fordham University), where he received the degree of LL.D. In 1854 he married Sophie Savage.
Shea turned his attention to literature, and was connected in an editorial capacity with Frank Leslie's publishing house, and later edited the Catholic News, but for many years his attention was given to historical research in preparation of his History of the Catholic Church in the United States (1886–92), the fourth volume of which was in process of publication at the time of his death in Elizabeth, New Jersey. A major research interest was French colonization and Jesuit missions in America. He edited the Historical Magazine from 1859 until 1865. In 1889 he became an editor of the Catholic News which supported him until his death.
Shea was connected with many historical societies in America and Europe, and was the first president of the Catholic Historical Society of the United States. He was the first person to be awarded the Laetare Medal by the University of Notre Dame in 1883.Georgetown University conferred on him the degree of LL.D. in recognition of his work as a Catholic historian. The John Gilmary Shea Papers, a collection of correspondence, manuscripts, and research materials, are preserved in the Georgetown University Library (Special Collections Division).