Montgomery Blair, American lieutenant and politician, 20th United States Postmaster General (b. 1813)

Montgomery Blair (May 10, 1813 – July 27, 1883) was an American politician and lawyer from Maryland. He served in the Lincoln administration cabinet as Postmaster-General from 1861 to 1864, during the Civil War. He was the son of Francis Preston Blair, elder brother of Francis Preston Blair Jr. and cousin of B. Gratz Brown.