Principal Officers and Chiefs of Mission, by Name: L

Note: Career Foreign Service appointees are asterisked.

• Alcee Louis La Branche (1806–1861)
  • Chargé d’Affaires, Texas (1837–1840)
• *Helen R. Meagher La Lime (1951–)
  • Ambassador Extraordinary and Plenipotentiary, Mozambique (2003–2006)
  • Ambassador Extraordinary and Plenipotentiary, Angola (2014–2017)
• *Alphonse F. La Porta (1939–)
  • Ambassador Extraordinary and Plenipotentiary, Mongolia (1997–2000)
• Henry Richardson Labouisse Jr. (1904–1987)
  • Ambassador Extraordinary and Plenipotentiary, Greece (1961–1965)
• William Sterling Byrd Lacy (1910–1979)
  • Ambassador Extraordinary and Plenipotentiary, Korea (1955)
• Philip Lader (1946–)
  • Ambassador Extraordinary and Plenipotentiary, United Kingdom (1997–2001)
• *Christopher L. LaFleur (1949–)
  • Ambassador Extraordinary and Plenipotentiary, Malaysia (2004–2007)
• Jewel Stradford Lafontant-Mankarious (1922–1997)
  • Ambassador at Large (1989–1993)
• Mark P. Lagon (1965–)
  • Ambassador at Large (2007–2009)
• *Lowell Bruce Laingen (1922–)
  • Ambassador Extraordinary and Plenipotentiary, Malta (1976–1979)
  • Chargé d’Affaires ad interim, Iran (1980)
• *Caroline Clendening Laise (1917–1991)
  • Ambassador Extraordinary and Plenipotentiary, Nepal (1966–1973)
  • Assistant Secretary of State for Public Affairs (1973–1975)
  • Director General of the Foreign Service (1975–1977)
• *Joseph Edward Lake (1941–)
  • Ambassador Extraordinary and Plenipotentiary, Mongolia (1990–1993)
  • Ambassador Extraordinary and Plenipotentiary, Albania (1994–1996)
• William Anthony Kirsopp Lake (1939–)
  • Director of Policy Planning (1977–1981)
• *Kamala S. Lakhdhir (?–)
  • Ambassador Extraordinary and Plenipotentiary, Malaysia (2016)
• Mirabeau Buonaparte Lamar (1798–1859)
  • Minister Resident, Argentina (1857)
  • Envoy Extraordinary and Minister Plenipotentiary, Nicaragua (1857)
  • Minister Resident, Costa Rica (1858–1859)
  • Minister Resident, Nicaragua (1858–1859)
• *Denis Lamb (1937–)
  • Representative of the U.S.A. to the Organization for Economic Cooperation and Development (Paris) (1987–1990)
• *Robert E. Lamb (1936–)
  • Assistant Secretary of State for Administration (1983–1985)
  • Assistant Secretary of State for Diplomatic Security (1987–1989)
  • Ambassador Extraordinary and Plenipotentiary, Cyprus (1990–1993)
• *Christopher Lambert (1959–)
  • Chargé d’Affaires ad interim, Dominican Republic (2010)
• Paul C. Lambert (1928–)
  • Ambassador Extraordinary and Plenipotentiary, Ecuador (1990–1992)
• *David Floyd Lambertson (1940–)
  • Ambassador Extraordinary and Plenipotentiary, Thailand (1991–1995)
• *Donald Wakeham Lamm (1914–1996)
  • Chargé d’Affaires, Ghana (1957)
• Christopher Landau (?–)
  • Ambassador Extraordinary and Plenipotentiary, Mexico (2019)
• *George Walter Landau (1920–)
  • Ambassador Extraordinary and Plenipotentiary, Paraguay (1972–1977)
  • Ambassador Extraordinary and Plenipotentiary, Chile (1977–1982)
  • Ambassador Extraordinary and Plenipotentiary, Venezuela (1982–1985)
• Sonia Landau (1937–)
  • Coordinator for International Communications and Information Policy (1988–1989)
• *Arthur Bliss Lane (1894–1956)
  • Envoy Extraordinary and Minister Plenipotentiary, Nicaragua (1933–1936)
  • Envoy Extraordinary and Minister Plenipotentiary, Estonia (1936–1937)
  • Envoy Extraordinary and Minister Plenipotentiary, Latvia (1936–1937)
  • Envoy Extraordinary and Minister Plenipotentiary, Lithuania (1936–1937)
  • Envoy Extraordinary and Minister Plenipotentiary, Yugoslavia (1937–1941)
  • Envoy Extraordinary and Minister Plenipotentiary, Costa Rica (1941–1942)
  • Ambassador Extraordinary and Plenipotentiary, Colombia (1942–1944)
  • Ambassador Extraordinary and Plenipotentiary, Poland (1944–1947)
• David J. Lane (1960–)
  • U.S. Representative to the United Nations Agencies for Food and Agriculture (Rome) (2012–2016)
• *George M. Lane (1928–)
  • Ambassador Extraordinary and Plenipotentiary, Yemen (1978–1981)
• Laurence William Lane Jr. (1919–2010)
  • Ambassador Extraordinary and Plenipotentiary, Australia (1985–1989)
  • Ambassador Extraordinary and Plenipotentiary, Nauru (1985–1989)
• *Lyle Franklin Lane (1926–2013)
  • Principal Officer, Cuba (1979)
  • Ambassador Extraordinary and Plenipotentiary, Uruguay (1979–1980)
  • Ambassador Extraordinary and Plenipotentiary, Paraguay (1980–1982)
• James T. Laney (1927–)
  • Ambassador Extraordinary and Plenipotentiary, Korea (1993–1996)
• Mark Langdale (1954–)
  • Ambassador Extraordinary and Plenipotentiary, Costa Rica (2005–2008)
• *John E. Lange (1948–)
  • Ambassador Extraordinary and Plenipotentiary, Botswana (1999–2002)
• *Leonard J. Lange (1949–)
  • Chargé d’Affaires ad interim, Burundi (1994)
• James McLellan Langley (1894–1968)
  • Ambassador Extraordinary and Plenipotentiary, Pakistan (1957–1959)
• John Mercer Langston (1829–1897)
  • Minister Resident/Consul General, Haiti (1877–1885)
  • Chargé d’Affaires, Dominican Republic (1883–1885)
• *Jerry P. Lanier (1952–)
  • Ambassador Extraordinary and Plenipotentiary, Uganda (2009–2012)
  • Chargé d’Affaires, Sudan (2016)
• Raphael O’Hara Lanier (1900–1962)
  • Envoy Extraordinary and Minister Plenipotentiary, Liberia (1946–1948)
• *Edward G. Lanpher (1942–)
  • Ambassador Extraordinary and Plenipotentiary, Zimbabwe (1991–1995)
• Robert Lansing (1864–1928)
  • Counselor (1914–1915)
  • Secretary of State (1915–1920)
  • Secretary of State ad interim (1915)
• *Jessica Lapenn (?–)
  • Chargé d’Affaires ad interim, South Africa (2019)
  • Representative of the U.S.A. to the African Union (2019)
• Barbara Mills Larkin (1951–)
  • Assistant Secretary of State for Legislative Affairs (1996–2001)
• Samuel Larned (1788–1846)
  • Chargé d’Affaires, Chile (1828–1829)
  • Chargé d’Affaires, Peru (1828–1837)
• *James A. Larocco (1948–)
  • Ambassador Extraordinary and Plenipotentiary, Kuwait (1997–2001)
• *Alan Philip Larson (1949–)
  • Representative of the U.S.A. to the Organization for Economic Cooperation and Development (Paris) (1990–1993)
  • Assistant Secretary of State for Economic, Energy, and Business Affairs (1996–1999)
  • Under Secretary for Economic Growth, Energy, and the Environment (1999–2005)
  • Career Ambassador (2004)
• Arthur Larson (1910–1993)
  • Director of the U.S. Information Agency (1956–1957)
• Charles W. Larson Jr. (1968–)
  • Ambassador Extraordinary and Plenipotentiary, Latvia (2007–2009)
• *Alexander Mark Laskaris (1967–)
  • Ambassador Extraordinary and Plenipotentiary, Guinea (2012–2015)
• Ronald Stephen Lauder (1944–)
  • Ambassador Extraordinary and Plenipotentiary, Austria (1986–1987)
• *Clint Arlen Lauderdale (1932–2009)
  • Ambassador Extraordinary and Plenipotentiary, Guyana (1984–1987)
• *Irwin Boyle Laughlin (1871–1941)
  • Envoy Extraordinary and Minister Plenipotentiary, Greece (1924–1926)
  • Ambassador Extraordinary and Plenipotentiary, Spain (1929–1933)
• Luis S. Lauredo (1949–)
  • Permanent Representative of the U.S.A. to the Organization of American States (Washington) (1999–2001)
• Franklin L. Lavin (1957–)
  • Ambassador Extraordinary and Plenipotentiary, Singapore (2001–2005)
• Sean P. Lawler (1972–)
  • Chief of Protocol (2017)
• Abbott Lawrence (1792–1855)
  • Envoy Extraordinary and Minister Plenipotentiary, United Kingdom (1849–1852)
• Albert Gallatin Lawrence (1836–1887)
  • Minister Resident, Costa Rica (1866–1868)
• *Loren E. Lawrence (1926–1992)
  • Ambassador Extraordinary and Plenipotentiary, Jamaica (1979–1982)
• M. Larry Lawrence (1926–1996)
  • Ambassador Extraordinary and Plenipotentiary, Switzerland (1994–1996)
• *Edward Burnett Lawson (1895–1962)
  • Envoy Extraordinary and Minister Plenipotentiary, Iceland (1949–1954)
  • Ambassador Extraordinary and Plenipotentiary, Israel (1954–1959)
• Michael Anderson Lawson (1953–)
  • Representative of the U.S.A. on the Council of the International Civil Aviation Organization (Montreal) (2014–2017)
• Alexander Robert Lawton (1818–1896)
  • Envoy Extraordinary and Minister Plenipotentiary, Austria (1887–1889)
  • Envoy Extraordinary and Minister Plenipotentiary, Russia (Not commissioned; nomination withdrawn before the Senate acted upon it.)
• George Washington Lay (1798–1860)
  • Chargé d’Affaires, Sweden (1842–1845)
• *Julius Gareche Lay (1872–1939)
  • Envoy Extraordinary and Minister Plenipotentiary, Honduras (1929–1935)
  • Envoy Extraordinary and Minister Plenipotentiary, Uruguay (1934)
  • Envoy Extraordinary and Minister Plenipotentiary, Uruguay (1935–1937)
• Howard H. Leach (1930–)
  • Ambassador Extraordinary and Plenipotentiary, France (2001–2005)
• *Joyce Ellen Leader (1942–)
  • Ambassador Extraordinary and Plenipotentiary, Guinea (1999–2000)
• *Barbara A. Leaf (1958–)
  • Ambassador Extraordinary and Plenipotentiary, United Arab Emirates (2014–2018)
• William Daniel Leahy (1875–1959)
  • Ambassador Extraordinary and Plenipotentiary, France (1940–1942)
• Thomas Vincent Learson (1912–1996)
  • Ambassador at Large (1975–1977)
• *John Charles Leary (1924–2002)
  • Representative of the U.S.A. to the United Nations Industrial Development Organization (Vienna) (1977–1980)
  • Chargé d’Affaires ad interim, Grenada (1988)
• William Hayne Leavell (1850–1930)
  • Envoy Extraordinary and Minister Plenipotentiary, Guatemala (1913–1918)
• *Joseph Evan LeBaron (1947–)
  • Ambassador Extraordinary and Plenipotentiary, Mauritania (2003–2006)
  • Ambassador Extraordinary and Plenipotentiary, Qatar (2008–2011)
• *Richard B. LeBaron (1951–)
  • Ambassador Extraordinary and Plenipotentiary, Kuwait (2004–2007)
• John Marshall Leddy (1914–1997)
  • Representative of the U.S.A. to the Organization for Economic Cooperation and Development (Paris) (1962–1965)
  • Assistant Secretary of State for European and Eurasian Affairs (1965–1969)
• *James Vela Ledesma (1941–)
  • Ambassador Extraordinary and Plenipotentiary, Gabon (1998–2001)
  • Ambassador Extraordinary and Plenipotentiary, Sao Tome and Principe (1998–2001)
• Charles Lee (1758–1815)
  • Secretary of State ad interim (1800)
• Joseph Wilcox Jenkins Lee (1870–1949)
  • Envoy Extraordinary and Minister Plenipotentiary, Ecuador (1905–1907)
  • Envoy Extraordinary and Minister Plenipotentiary, Honduras (1907)
  • Envoy Extraordinary and Minister Plenipotentiary, Guatemala (1907)
  • Envoy Extraordinary and Minister Plenipotentiary, Guatemala (1907)
• Ernest W. Lefever (1919–2009)
  • Assistant Secretary of State for Democracy, Human Rights, and Labor (Not commissioned; nomination withdrawn before the Senate acted upon it.)
• Hugh Swinton Legare (1797–1843)
  • Chargé d’Affaires, Belgium (1832–1836)
  • Secretary of State ad interim (1843)
• Charles William LeGendre (1830–1899)
  • Minister Resident, Argentina (To be commissioned to the Argentine Republic. Not commissioned; nomination not confirmed by the Senate.)
• Ronald Frank Lehman II (1946–)
  • Director of the U.S. Arms Control and Disarmament Agency (1989–1993)
• *Donald Charles Leidel (1927–)
  • Ambassador Extraordinary and Plenipotentiary, Bahrain (1983–1986)
• Monroe Leigh (1919–2001)
  • Legal Adviser (1974–1977)
• John G.A. Leishman (1857–1924)
  • Envoy Extraordinary and Minister Plenipotentiary, Switzerland (1897–1901)
  • Envoy Extraordinary and Minister Plenipotentiary, Turkey (1900–1906)
  • Ambassador Extraordinary and Plenipotentiary, Turkey (1906–1909)
  • Ambassador Extraordinary and Plenipotentiary, Italy (1909–1911)
  • Ambassador Extraordinary and Plenipotentiary, Germany (1911–1913)
• Wilbert John LeMelle (1931–)
  • Ambassador Extraordinary and Plenipotentiary, Kenya (1977–1980)
  • Ambassador Extraordinary and Plenipotentiary, Seychelles (1977–1980)
• *Michael Craig Lemmon (1946–)
  • Ambassador Extraordinary and Plenipotentiary, Armenia (1998–2001)
• Alfonso E. Lenhardt (1943–)
  • Ambassador Extraordinary and Plenipotentiary, Tanzania (2009–2013)
• *John P. Leonard (1940–)
  • Ambassador Extraordinary and Plenipotentiary, Suriname (1990–1993)
  • Chargé d’Affaires ad interim, Nicaragua (1990)
• *Mary Beth Leonard (1962–)
  • Ambassador Extraordinary and Plenipotentiary, Mali (2011–2014)
  • Representative of the U.S.A. to the African Union (2016–2019)
  • Ambassador Extraordinary and Plenipotentiary, Nigeria (2019)
• *Walter Anderson Leonard (1880–1955)
  • Chargé d’Affaires ad interim, Estonia (1940)
• *William Leonhart (1919–1997)
  • Ambassador Extraordinary and Plenipotentiary, Tanzania (1962–1965)
  • Ambassador Extraordinary and Plenipotentiary, Socialist Federal Republic of Yugoslavia (1969–1971)
• Louis Abraham Lerner (1935–1984)
  • Ambassador Extraordinary and Plenipotentiary, Norway (1977–1980)
• Robert Perkins Letcher (1788–1861)
  • Envoy Extraordinary and Minister Plenipotentiary, Mexico (1849–1852)
• Mara M. Letica (1955–)
  • Ambassador Extraordinary and Plenipotentiary, Croatia (Nomination of September 9, 1992, not acted upon by the Senate.)
• *Burton Levin (1930–)
  • Ambassador Extraordinary and Plenipotentiary, Burma (1987–1990)
• Fay Hartog Levin (1948–)
  • Ambassador Extraordinary and Plenipotentiary, Netherlands (2009–2012)
• *Jeffrey D. Levine (1955–)
  • Ambassador Extraordinary and Plenipotentiary, Estonia (2012–2015)
• Suzan G. LeVine (1969–)
  • Ambassador Extraordinary and Plenipotentiary, Switzerland (2014–2017)
  • Ambassador Extraordinary and Plenipotentiary, Liechtenstein (2014–2017)
• *Melvyn Levitsky (1938–)
  • Ambassador Extraordinary and Plenipotentiary, Bulgaria (1984–1987)
  • Executive Secretary (1987–1989)
  • Assistant Secretary of State for International Narcotics and Law Enforcement Affairs (1989–1993)
  • Ambassador Extraordinary and Plenipotentiary, Brazil (1994–1998)
• Jacob L. Lew (1955–)
  • Deputy Secretary of State for Management and Resources (2009–2010)
• *Arthur Winston Lewis (1926–)
  • Ambassador Extraordinary and Plenipotentiary, Sierra Leone (1983–1986)
• Charles Hance Lewis (1816–)
  • Minister Resident, Portugal (1870–1875)
• *Charles William Lewis Jr. (1898–1988)
  • Chargé d’Affaires ad interim, Pakistan ()
• Delano Eugene Lewis Jr. (1938–)
  • Ambassador Extraordinary and Plenipotentiary, South Africa (1999–2001)
• Edward Parke Custis Lewis (1837–1892)
  • Minister Resident/Consul General, Portugal (1885–1889)
• *Geoffrey Whitney Lewis (1910–1992)
  • Ambassador Extraordinary and Plenipotentiary, Mauritania (1965–1967)
  • Ambassador Extraordinary and Plenipotentiary, Central African Republic (1967–1970)
• *Harrison Lewis (1905–1985)
  • Chargé d’Affaires ad interim, Malta ()
• *Samuel Winfield Lewis (1930–2014)
  • Assistant Secretary of State for International Organization Affairs (1975–1977)
  • Ambassador Extraordinary and Plenipotentiary, Israel (1977–1985)
  • Director of Policy Planning (1993–1994)
• *Dawn M. Liberi (1954–)
  • Ambassador Extraordinary and Plenipotentiary, Burundi (2012–2016)
  • Ambassador Extraordinary and Plenipotentiary, Mauritania (Nomination of May 1, 2006, not acted upon by the Senate.)
• Evelyn Simonowitz Lieberman (1944–)
  • Under Secretary of State for Public Diplomacy and Public Affairs (1999–2001)
• Walter Scott Light (1931–)
  • Ambassador Extraordinary and Plenipotentiary, Ecuador (Nomination of July 25, 1992, not acted upon by the Senate.)
• *Edwin Allan Lightner Jr. (1907–1990)
  • Ambassador Extraordinary and Plenipotentiary, Libya (1963–1965)
• *Rose M. Likins (1959–)
  • Ambassador Extraordinary and Plenipotentiary, El Salvador (2000–2003)
  • Ambassador Extraordinary and Plenipotentiary, Peru (2010–2013)
• James Roderick Lilley (1935–2009)
  • Ambassador Extraordinary and Plenipotentiary, Korea (1986–1989)
  • Ambassador Extraordinary and Plenipotentiary, China (1989–1991)
• *John W. Limbert (1943–)
  • Ambassador Extraordinary and Plenipotentiary, Mauritania (2000–2003)
  • Chargé d’Affaires, Sudan (2005)
• *Joseph A. Limprecht (1946–)
  • Ambassador Extraordinary and Plenipotentiary, Albania (1999–2002)
• Levi Lincoln (1749–1820)
  • Secretary of State ad interim (1801)
• Robert Todd Lincoln (1843–1926)
  • Envoy Extraordinary and Minister Plenipotentiary, United Kingdom (1889–1893)
• Harold Francis Linder (1900–1981)
  • Assistant Secretary of State for Economic, Energy, and Business Affairs (1952–1953)
  • Ambassador Extraordinary and Plenipotentiary, Canada (1968–1969)
• *David Lindwall (?–)
  • Chargé d’Affaires ad interim, Sweden (2018)
• *John Andrew Linehan Jr. (1924–2005)
  • Ambassador Extraordinary and Plenipotentiary, Sierra Leone (1977–1980)
• Steve A. Linick (1963–)
  • Inspector General of the Department of State and the Foreign Service (2013)
• *Marisa R. Lino (1950–)
  • Ambassador Extraordinary and Plenipotentiary, Albania (1996–1999)
• Sol Myron Linowitz (1913–2005)
  • Permanent Representative of the U.S.A. to the Organization of American States (Washington) (1966–1969)
• Mark William Lippert (1973–)
  • Ambassador Extraordinary and Plenipotentiary, Korea (2014–2017)
• *David C. Litt (1949–)
  • Ambassador Extraordinary and Plenipotentiary, United Arab Emirates (1995–1998)
• Edward Campbell Little (1858–1924)
  • Agent/Consul General, Egypt (1892–1893)
• *Edward Southard Little (1918–2004)
  • Ambassador Extraordinary and Plenipotentiary, Chad (1974–1976)
• *Earle D. Litzenberger (?–)
  • Ambassador Extraordinary and Plenipotentiary, Azerbaijan (2019)
• Edward Livingston (1764–1836)
  • Secretary of State (1831–1833)
  • Envoy Extraordinary and Minister Plenipotentiary, France (1833–1835)
• Robert R. Livingston (1746–1813)
  • Secretary of Foreign Affairs Under the Continental Congress (1781)
  • Minister Plenipotentiary, France (1801–1804)
• Van Brugh Livingston (1792–1868)
  • Chargé d’Affaires, Ecuador (1848–1849)
• William Livingston (1723–1790)
  • Minister Plenipotentiary, Netherlands (Elected on June 23, 1785, to be Minister Plenipotentiary to the United Netherlands; declined appointment.)
• *Hugo Llorens (1954–)
  • Ambassador Extraordinary and Plenipotentiary, Honduras (2008–2011)
• Eugene Murphy Locke (1918–1972)
  • Ambassador Extraordinary and Plenipotentiary, Pakistan (1966–1967)
• Gary Locke (1950–)
  • Ambassador Extraordinary and Plenipotentiary, China (2011–2014)
• Jesse Dwight Locker (1891–1955)
  • Ambassador Extraordinary and Plenipotentiary, Liberia (1953–1955)
• Henry Cabot Lodge Jr. (1902–1985)
  • Representative of the U.S.A. to the United Nations (1953–1960)
  • Ambassador Extraordinary and Plenipotentiary, South Vietnam (1963–1964)
  • Ambassador Extraordinary and Plenipotentiary, South Vietnam (1965–1967)
  • Ambassador at Large (1967–1968)
  • Ambassador Extraordinary and Plenipotentiary, Germany (1968–1969)
  • Personal Representative of the President, Holy See (1977)
• John Davis Lodge (1903–1985)
  • Ambassador Extraordinary and Plenipotentiary, Spain (1955–1961)
  • Ambassador Extraordinary and Plenipotentiary, Argentina (1969–1973)
  • Ambassador Extraordinary and Plenipotentiary, Switzerland (1983–1985)
• James Isaac Loeb Jr. (1908–1992)
  • Ambassador Extraordinary and Plenipotentiary, Peru (1961–1962)
  • Ambassador Extraordinary and Plenipotentiary, Guinea (1963–1965)
• John Langeloth Loeb Jr. (1930–)
  • Ambassador Extraordinary and Plenipotentiary, Denmark (1981–1983)
• *Robert Geers Loftis (1956–)
  • Ambassador Extraordinary and Plenipotentiary, Lesotho (2001–2004)
• *Gerald J. Loftus (1952–)
  • Chargé d’Affaires ad interim, Luxembourg (2002)
• Thomas A. Loftus (1945–)
  • Ambassador Extraordinary and Plenipotentiary, Norway (1993–1997)
• Cornelius Ambrose Logan (1832–1899)
  • Envoy Extraordinary and Minister Plenipotentiary, Chile (1873–1876)
  • Minister Resident, El Salvador (1879–1882)
  • Minister Resident, Costa Rica (1879–1882)
  • Minister Resident, Honduras (1879–1882)
  • Minister Resident, Guatemala (1879–1882)
  • Minister Resident, Nicaragua (1879–1882)
  • Envoy Extraordinary and Minister Plenipotentiary, Chile (1882–1885)
• John Alexander Logan (1826–1886)
  • Envoy Extraordinary and Minister Plenipotentiary, Mexico (1865)
• *Kent D. Logsdon (?–)
  • Chargé d’Affaires ad interim, Germany (2018)
• Carmen L. Lomellin (1950–)
  • Permanent Representative of the U.S.A. to the Organization of American States (Washington) (2009)
• Boaz Walton Long (1876–1962)
  • Envoy Extraordinary and Minister Plenipotentiary, El Salvador (1914–1917)
  • Envoy Extraordinary and Minister Plenipotentiary, Cuba (1919–1921)
  • Envoy Extraordinary and Minister Plenipotentiary, Nicaragua (1936–1938)
  • Envoy Extraordinary and Minister Plenipotentiary, Ecuador (1938–1942)
  • Ambassador Extraordinary and Plenipotentiary, Ecuador (1942–1943)
  • Ambassador Extraordinary and Plenipotentiary, Guatemala (1943–1945)
• John G. Long (1846–1903)
  • Agent/Consul General, Egypt (1899–1903)
• Samuel Miller Breckinridge Long (1881–1958)
  • Third Assistant Secretary of State (1917–1920)
  • Ambassador Extraordinary and Plenipotentiary, Italy (1933–1936)
  • Assistant Secretary of State (1940–1944)
• James Longstreet (1821–1904)
  • Minister Resident, Turkey (1880–1881)
• Cyrus O. Loomis (?–)
  • Minister Resident/Consul General, Haiti (Not commissioned; nomination rejected by the Senate.)
• Francis Butler Loomis (1861–1948)
  • Envoy Extraordinary and Minister Plenipotentiary, Venezuela (1897–1901)
  • Envoy Extraordinary and Minister Plenipotentiary, Portugal (1901–1902)
  • Assistant Secretary of State (1903–1905)
  • Secretary of State ad interim (1905)
• *Matthew James Looram Jr. (1921–2004)
  • Ambassador Extraordinary and Plenipotentiary, Benin (1969–1971)
  • Ambassador Extraordinary and Plenipotentiary, Somalia (1972–1973)
• William Paine Lord (1838–1911)
  • Envoy Extraordinary and Minister Plenipotentiary, Argentina (1899–1903)
  • Minister Resident/Consul General, Iran (1899)
• *Winston Lord (1937–)
  • Director of Policy Planning (1973–1977)
  • Ambassador Extraordinary and Plenipotentiary, China (1985–1989)
  • Assistant Secretary of State for East Asian and Pacific Affairs (1993–1997)
• George Bailey Loring (1817–1891)
  • Minister Resident/Consul General, Portugal (1889–1890)
• George Van Ness Lothrop (1817–1897)
  • Envoy Extraordinary and Minister Plenipotentiary, Russia (1885–1888)
• *John Lewis Loughran (1921–2006)
  • Ambassador Extraordinary and Plenipotentiary, Somalia (1975–1978)
• John J. Louis Jr. (1925–1995)
  • Ambassador Extraordinary and Plenipotentiary, United Kingdom (1981–1983)
• Donold Bradford Lourie (1899–1990)
  • Under Secretary of State for Management (1953–1954)
• Robert Abercrombie Lovett (1895–1986)
  • Under Secretary of State (1947–1949)
• Frederick Ferdinand Low (1828–1894)
  • Envoy Extraordinary and Minister Plenipotentiary, China (1869–1873)
• *Stephen Low (1927–2010)
  • Ambassador Extraordinary and Plenipotentiary, Zambia (1976–1979)
  • Ambassador Extraordinary and Plenipotentiary, Nigeria (1979–1981)
  • Director of the Foreign Service Institute (1982–1987)
• James Russell Lowell (1819–1891)
  • Envoy Extraordinary and Minister Plenipotentiary, Spain (1877–1880)
  • Envoy Extraordinary and Minister Plenipotentiary, United Kingdom (1880–1885)
• Barry F. Lowenkron (1952–)
  • Assistant Secretary of State for Democracy, Human Rights, and Labor (2005–2007)
• *James Gordon Lowenstein (1927–)
  • Ambassador Extraordinary and Plenipotentiary, Luxembourg (1977–1981)
• *Arthur L. Lowrie (1930–)
  • Principal Officer, Iraq (1975)
• Frank E. Loy (1928–)
  • Assistant Secretary of State for Population, Refugees, and Migration Affairs (1980–1981)
  • Under Secretary of State for Civilian Security, Democracy, and Human Rights (1998–2001)
• Ignacio E. Lozano Jr. (1927–)
  • Ambassador Extraordinary and Plenipotentiary, El Salvador (1976–1977)
• *Donald Lu (1966–)
  • Chargé d’Affaires ad interim, Azerbaijan (2010)
  • Ambassador Extraordinary and Plenipotentiary, Albania (2014–2018)
  • Ambassador Extraordinary and Plenipotentiary, Kyrgyzstan (2018)
• Ann Clare Boothe Luce (1903–1987)
  • Ambassador Extraordinary and Plenipotentiary, Italy (1953–1956)
  • Ambassador Extraordinary and Plenipotentiary, Brazil (1959)
• Patrick Joseph Lucey (1918–2014)
  • Ambassador Extraordinary and Plenipotentiary, Mexico (1977–1979)
• *Lewis W. Lucke (1951–)
  • Ambassador Extraordinary and Plenipotentiary, Swaziland (2004–2005)
• *William Henry Luers (1929–)
  • Ambassador Extraordinary and Plenipotentiary, Venezuela (1978–1982)
  • Ambassador Extraordinary and Plenipotentiary, Czechoslovakia (1983–1986)
• *Alan Wood Lukens (1924–2019)
  • Ambassador Extraordinary and Plenipotentiary, Congo (Brazzaville) (1984–1987)
  • Chargé d’Affaires ad interim, Congo (Brazzaville) ()
  • Chargé d’Affaires ad interim, Chad ()
  • Chargé d’Affaires ad interim, Central African Republic ()
  • Chargé d’Affaires ad interim, Gabon ()
• *Lewis A. Lukens (1963–)
  • Ambassador Extraordinary and Plenipotentiary, Guinea-Bissau (2011–2014)
  • Ambassador Extraordinary and Plenipotentiary, Senegal (2011–2014)
• *George Quincey Lumsden Jr. (1930–)
  • Ambassador Extraordinary and Plenipotentiary, United Arab Emirates (1982–1986)
• *Jeffrey John Lunstead (1947–)
  • Ambassador Extraordinary and Plenipotentiary, Maldives (2003–2006)
  • Ambassador Extraordinary and Plenipotentiary, Sri Lanka (2003–2006)
• *Samuel Eldred Lupo (1933–)
  • Ambassador Extraordinary and Plenipotentiary, Guinea (1987–1990)
• *Matthew R. Lussenhop (?–)
  • Chargé d’Affaires ad interim, Belgium (2018)
• Douglas Edward Lute (1952–)
  • U.S. Permanent Representative on the Council of the North Atlantic Treaty Organization (2013–2017)
• *Jack Wilson Lydman (1914–)
  • Ambassador Extraordinary and Plenipotentiary, Malaysia (1969–1973)
• *Princeton Nathan Lyman (1935–)
  • Ambassador Extraordinary and Plenipotentiary, Nigeria (1986–1989)
  • Assistant Secretary of State for Population, Refugees, and Migration Affairs (1989–1992)
  • Ambassador Extraordinary and Plenipotentiary, South Africa (1992–1995)
  • Assistant Secretary of State for International Organization Affairs (1997–1998)
• *Andrew Green Lynch (1902–1966)
  • Chargé d’Affaires ad interim, Somalia (1960)
  • Ambassador Extraordinary and Plenipotentiary, Somalia (1960–1962)
  • Chargé d’Affaires ad interim, Libya ()
• Patricia Gates Lynch (1926–2011)
  • Ambassador Extraordinary and Plenipotentiary, Comoros (1986–1989)
  • Ambassador Extraordinary and Plenipotentiary, Madagascar (1986–1989)
• *Sarah-Ann Lynch (?–)
  • Ambassador Extraordinary and Plenipotentiary, Guyana (2019)
• *Stephen R. Lyne (1935–)
  • Ambassador Extraordinary and Plenipotentiary, Ghana (1987–1989)
• *Cecil Burton Lyon (1903–1993)
  • Ambassador Extraordinary and Plenipotentiary, Chile (1956–1958)
  • Ambassador Extraordinary and Plenipotentiary, Sri Lanka (1964–1967)
  • Ambassador Extraordinary and Plenipotentiary, Maldives (1965–1967)
• *David L. Lyon (1951–)
  • Ambassador Extraordinary and Plenipotentiary, Fiji (2002–2005)
  • Ambassador Extraordinary and Plenipotentiary, Tonga (2002–2005)
  • Ambassador Extraordinary and Plenipotentiary, Nauru (2002–2005)
  • Ambassador Extraordinary and Plenipotentiary, Tuvalu (2002–2005)
  • Ambassador Extraordinary and Plenipotentiary, Kiribati (2003–2005)
• Ernest Lyon (1860–1938)
  • Minister Resident/Consul General, Liberia (1903–1910)