Henry Pinckney McCain (January 23, 1861 – July 25, 1941) was an American military officer who was Adjutant General of the United States Army from 1914 to 1918.

He entered and later graduated, 20th in a class of 37, from the United States Military Academy (USMA) at West Point, New York, in June 1885.

Among his classmates there included several men who would later rise to the rank of brigadier general or higher in their military careers, such as Joseph E. Kuhn, Charles H. Muir, John D. Barrette, Robert A.

He served as the acting assistant adjutant general for U.S. forces in the Philippines, but had to return to the United States in September due to illness.

[6] In June 1920, McCain reverted to his permanent peacetime rank of colonel and served as adjutant of the Sixth Corps Area until his retirement in July 1921.

He died in Washington on July 25, 1941, shortly before the United States was to enter World War II, and is buried in Arlington National Cemetery.