
The United States Under Secretary of the Army is the second-highest ranking civilian official of the United States Department of the Army, serving directly under the United States Secretary of the Army. The Secretary and Under Secretary, together with two military officers, the Chief of Staff of the United States Army and the Vice Chief of Staff of the United States Army, constitute the senior leaders of the United States Army.

Stephen Ailes was a prominent member of the District of Columbia Bar and a partner in the firm of Steptoe & Johnson. He served as the United States Under Secretary of the Army from February 9, 1961 to January 28, 1964 and as United States Secretary of the Army from January 28, 1964 to July 1, 1965. He received his undergraduate education at Princeton University, and attended the law school of West Virginia University, where he was a member of Phi Kappa Psi fraternity.

James R. Ambrose was an American aerospace executive who was United States Under Secretary of the Army from 1981 to 1988.

Norman (Norm) Ralph Augustine is a U.S. aerospace businessman who served as United States Under Secretary of the Army from 1975 to 1977. Augustine served as chairman and CEO of the Lockheed Martin Corporation. He was chairman of the Review of United States Human Space Flight Plans Committee.

Thaddeus R. Beal was the United States Under Secretary of the Army from March 8, 1969, through September 21, 1971.

Kenneth E. BeLieu was the United States Assistant Secretary of the Navy 1961-65, Under Secretary of the Navy in 1965; Under Secretary of the Army 1971-73; and then director of the National Petroleum Council in the late 1970s.

Karl Robin Bendetsen was an American colonel who served in Washington Army National Guard during the World War II and later as the Under Secretary of the Army. Bendetsen is remembered primarily for his role as an architect of the internment of Japanese Americans during World War II.

Romer Leslie "Les" Brownlee served as the Undersecretary of the Army from November 2001 to May 2003 and as Acting United States Secretary of the Army from 10 May 2003 until his resignation effective 2 December 2004, staying at the Undersecretary's office. Bill Gertz wrote that Donald Rumsfeld did not wish to name a non-CEO to the job of Secretary.

Brad Rogers Carson is an American lawyer and politician from the state of Oklahoma who served as the Acting Under Secretary of Defense for Personnel and Readiness from 2015–16. In that role, he initiated a number of notable reforms to include opening up all combat positions to women, open service by transgender service members, and new recruiting and retention practices.

Gregory Robert Dahlberg was United States Under Secretary of the Army from 2000 to 2001.

William Henry Draper Jr. was a 20th-century American army officer, banker, government official, and diplomat.

Eric Kenneth Fanning is an American public servant who is the current President and CEO of Aerospace Industries Association and served as the 22nd United States Secretary of the Army, holding office from May 18, 2016 to January 20, 2017. Prior to his appointment as Secretary of the Army, Fanning was the 24th United States Under Secretary of the Air Force. He was the first openly gay head of any service in the U.S. military.

Charles C. Finucane was an American government official, and banking and investments executive.

Nelson McCain Ford was United States Under Secretary of the Army from 2007 to 2009.

Preston Murdoch Geren, III, known as Pete Geren is an American politician who served as the 20th United States Secretary of the Army from July 16, 2007 to September 16, 2009. He is a Democratic former member of the United States House of Representatives from Texas's 12th congressional district. He is currently president of the Sid W. Richardson Foundation in Fort Worth, Texas and later chaired of the Institute for Defense Analyses in Alexandria, Virginia.

Gordon Gray was an official in the government of the United States during the administrations of Harry Truman (1945–53) and Dwight Eisenhower (1953–61) associated with defense and national security.

Paul Robert Ignatius is an American government official who served as Secretary of the Navy between 1967 and 1969 and was the Assistant Secretary of Defense during the Lyndon Johnson Administration.

Earl D. Johnson was the 4th United States Under Secretary of the Army from 1952 to 1954.

Walter Barber LaBerge (1924–2004) was an aerospace engineer and defense industry executive who served as United States Under Secretary of the Army from 1977 to 1980.

Earl G. Matthews is an American government official and attorney who held senior positions within the Department of the Army and at the White House during the administration of President Donald J. Trump. Matthews was a member of Trump's Department of Defense transition team and was appointed as a Special Assistant to the Secretary of Defense, James N. Mattis on January 20, 2017. Matthews was subsequently appointed as the Principal Deputy General Counsel of the Army on June 21, 2019. He served as Acting General Counsel of the Army from June 21, 2017 until James E. McPherson was sworn in as General Counsel on January 2, 2018.

Ryan D. McCarthy is an American politician, business executive and former United States Army Ranger serving as the 24th and current United States Secretary of the Army.

David E. McGiffert was a United States lawyer and Pentagon official who dealt with domestic security during the social upheavals of the late 1960s.

James Edwin McPherson is an American government official and retired United States Navy rear admiral. He has served as the Acting United States Under Secretary of the Army since July 23, 2019, and was sworn into the position full-time on March 25, 2020 following confirmation by the Senate. He concurrently served as the General Counsel of the Army from 2018 to 2020. He was designated as Acting United States Secretary of the Navy on April 7, 2020, following the resignation of Thomas Modly.

Hugh Meglone Milton II was a major general of the United States Army during World War II who served as United States Under Secretary of the Army from 1958 to 1961.

Patrick Joseph Murphy was the thirty-second United States Under Secretary of the Army. The Washington Post referred to him as the "Soldier's Secretary." He was the first veteran of the Iraq War to be elected to the United States House of Representatives, representing Pennsylvania's 8th congressional district from 2007–2011. Murphy is a former anchor of Taking the Hill on MSNBC. Murphy is currently a Senior Managing Director at Ankura Consulting in Philadelphia and the Distinguished Chair of Innovation at the United States Military Academy.
Joseph Robert Reeder is a United States lawyer who served as United States Under Secretary of the Army from 1993 to 1997.

Stanley Rogers Resor was an American lawyer, military officer, and government official.

Bernard Daniel Rostker was Principal Deputy Assistant Secretary of the Navy from 1977 to 1979; Director of the United States Selective Service System from 1979 to 1981; Assistant Secretary of the Navy from 1994 to 1998; Under Secretary of the Army from 1998 to 2000; and Under Secretary of Defense for Personnel and Readiness in 2000-2001. From 1996 to 2001, he also served as Special Assistant to the Deputy Secretary of Defense for Gulf War Illnesses.
John W. Shannon was United States Under Secretary of the Army from 1989 to 1993.

Herman R. Staudt was United States Under Secretary of the Army from 1973 to 1975.
Michael Patrick William Stone was a U.S. business executive and federal government administrator. He served as the United States Secretary of the Army between 1989 and 1993.

Tracy Stebbins Voorhees served as Under Secretary of the United States Army from August 1949 to April 1950. He held numerous positions within the U.S. Government as a civilian. A practicing attorney, Voorhees, with the Judge Advocate General's Department, he served as part of the Surgeon General's office in the European and Pacific theatres during World War II. After the War, he served in various positions in the Defense Department.
Robert Michael Walker is the former United States Under Secretary of the Army (1997-1998).

Joseph W. Westphal is an American politician and diplomat who was most recently the United States Ambassador to Saudi Arabia. He served as the 30th United States Under Secretary of the Army from 2009 to 2014.