John Alexander Logan (February 9, 1826 – December 26, 1886) was an American soldier and politician. He served in the Mexican–American War and was a general in the Union Army in the American Civil War. He served the state of Illinois as a state Representative, a U.S. Representative, and a U.S. Senator and was an unsuccessful candidate for Vice President of the United States as James G. Blaine's running mate in the election of 1884. As the 3rd Commander-in-Chief of the Grand Army of the Republic, he is regarded as the most important figure in the movement to recognize Memorial Day (originally known as Decoration Day) as an official holiday.
His likeness appears on a statue at the center of Logan Circle, Washington, D.C. He is also honored with a statue in Grant Park in Chicago, Illinois. Memorial Park in Houston, Texas was formerly Camp Logan named after him. He is the honoree of Logan County, Kansas; Logan County, Oklahoma; Logan County, Colorado; Logan County, North Dakota; and Logan Square, Chicago, which is the neighborhood chosen to mark Illinois' centennial. Logan is one of only three people mentioned by name in the Illinois state song. Upon his death, he lay in state in the United States Capitol rotunda. He is the father of U.S. Army officer and Medal of Honor recipient John Alexander Logan Jr. (1865–1899).