James W. Jackson (ca. 1824 – May 24, 1861) was an ardent secessionist and the proprietor of the Marshall House, an inn located in the city of Alexandria, Virginia, at the beginning of the American Civil War. He is known for flying a large Confederate flag – the "Stars and Bars" variant – atop his inn that was visible to President Abraham Lincoln from Washington, D.C. and for killing Col. Elmer Ellsworth in an incident that marked the first conspicuous casualty and the first killing of a Union officer in the Civil War. Jackson was killed immediately after he killed Ellsworth. While losing their lives, both gained fame as martyrs to their respective causes.