James Glas Grindlay (February 14, 1840 – October 19, 1907) was a Union Army officer in the American Civil War and a recipient of the United States military's highest decoration, the Medal of Honor, for his actions during the Battle of Five Forks. He served with the 146th New York Volunteer Infantry Regiment and commanded that unit for the last year of the war. He twice briefly led his brigade after his superior officers became casualties, and was brevetted brigadier general shortly before the end of the conflict.