Joseph George Rosengarten (born in Philadelphia, Pennsylvania, 14 July 1835; died 14 January 1921) was a Philadelphia lawyer and historian.
He was graduated from the University of Pennsylvania in 1852, studied law, was admitted to the bar in 1856, studied in Heidelberg in 1857, and practised law in Philadelphia. During the Civil War, he served on the staff of General John F. Reynolds in the Army of the Potomac.
He delivered numerous addresses before various literary and charitable associations, including one before the Pennsylvania Historical Society on the “Life and Public Services of General John F. Reynolds” (Philadelphia, 1880), and contributed frequently to periodicals. He is the author of The German Soldier in the Wars of the United States (Philadelphia, 1881).