John Rose Greene Hassard (b. in New York, U.S.A., 4 September 1836; d. in that city, 18 April 1888) was an editor and historian. His parents were Episcopalians, his mother being a granddaughter of Commodore Nicholson of Revolutionary fame. He became a Catholic at the age of fifteen and, after graduating at St. John's College, New York, entered the diocesan seminary, intending to study for the priesthood.
Ill-health, however, forced him to abandon this idea and he turned to literature. He was the first editor of the Catholic World magazine, and assistant editor of the Chicago Republican and of the American Cyclopedia, and joined the editorial staff of the New York Tribune, on which paper his principal work was that of literary and musical critic. In the latter capacity he was one of the Wagner school of modern music, writing letters descriptive of the festivals at Bayreuth. Most of his literary life was spent as a journalist, but in addition to this he wrote a very comprehensive life of Archbishop John Hughes of New York, and a short one of the Pope Pius IX. He also prepared a History of the United States in both extended and abridged forms for use in Catholic colleges and schools.