1) James V. Forrestal
Sep 17, 1947 - Mar 28, 1949
13) Donald H. Rumsfeld
Nov 20, 1975 - Jan 20, 1977
2) Louis A. Johnson
Mar 28, 1949 - Sep 19, 1950		 14) Harold Brown
Jan 21, 1977 - Jan 20, 1981
3) George C. Marshall
Sep 21, 1950 - Sep 12, 1951 		15) Caspar W. Weinberger
Jan 21, 1981 - Nov 23, 1987
4) Robert A. Lovett
Sep 17, 1951 - Jan 20, 1953 		16) Frank C. Carlucci
Nov 23, 1987 - Jan 20, 1989
5) Charles E. Wilson
Jan 28, 1953 - Oct 8, 1957 		17) Richard B. Cheney
Mar 21, 1989 - Jan 20, 1993
6) Neil H. McElroy
Oct 9, 1957 - Dec 1, 1959 		18) Les Aspin
Jan 21, 1993 - Feb 3, 1994
7) Thomas S. Gates
Dec 2, 1959 - Jan 20, 1961		 19) William J. Perry
Feb 3, 1994 - Jan 23, 1997
8) Robert S. McNamara
Jan 21, 1961 - Feb 29, 1968		 20) William S. Cohen
Jan 24, 1997 - Jan 20, 2001
9) Clark M. Clifford
Mar 1, 1968 - Jan 20, 1969		 21)

Donald H. Rumsfeld
Jan 20, 2001 - Dec 18, 2006

10)

Melvin R. Laird
Jan 22, 1969 - Jan 29, 1973

 22)

Robert M. Gates
Dec 18, 2006 - July 1, 2011
11) Elliot L. Richardson
Jan 30, 1973 - May 24, 1973		 23)

Leon E. Panetta
July 1, 2011 - Feb. 27, 2013
12) James R. Schlesinger
Jul 2, 1973 - Nov 19, 1975		 24)

Chuck Hagel
Feb. 27, 2013 - Present