The leaders of the League of Nations consisted of a secretary-general, deputy secretary-general and a president of the Assembly selected from member states.
| No. | Portrait | Secretary General | Took office | Left office | Time in office | Country |
|---|---|---|---|---|---|---|
| 1 | Sir Eric Drummond (1876–1951) | 1 August 1920 | 2 July 1933 | 12 years, 336 days |  United Kingdom | |
| 2 | Joseph Avenol (1879–1952) | 3 July 1933 | 31 August 1940 | 7 years, 59 days |  France | |
| 3 | Seán Lester (1888–1959) | 31 August 1940 | 18 April 1946 | 5 years, 230 days |  Ireland |
| No. | Portrait | Name | Term | Country |
|---|---|---|---|---|
| 1 |  | Jean Monnet | 1919–1923 | France |
| 2 |  | Joseph Avenol | 1923–1932 | France |
| 3 |  | Pablo de Azcárate | 1933–1936 |  Spain |
 | Massimo Pilotti |  Italy | ||
| 4 |  | Seán Lester | 1937–1940 | Ireland |
| 5 | Francis Paul Walters | 1940-1946 | United Kingdom |
 |
| Nation | Name | Term |
|---|---|---|
 United States | Raymond B. Fosdick | 1919 (provisional) |
| Italy | Bernardo Attolico | 1919–1920 |
 Japan | Nitobe Inazo | 1919–1926 |
| Italy | Dionisio Anzilotti | 1920–1921 |
 Germany | Albert Dufour-Feronce | 1927–1932 |
| Italy | Giacomo Paulucci di Calboli | 1927–1932 |
| Japan | Yotaro Sugimura | 1927–1933 |
| Germany | Ernst Trendelenburg | 1932–1933 |
| United Kingdom | Francis Paul Walters | 1933–1939 |
 Soviet Union | Vladimir Sokoline | 1937–1939 |
 Argentina | Luis Podestá Costa | 1938–1943 |
 Greece | Thanassis Aghnides | 1939–1942 |
| Nation | Portrait | Name | Term |
|---|---|---|---|
| France |  | Léon Bourgeois | 1920 |
 Belgium |  | Paul Hymans 1st time | 1920–1921 |
 Netherlands |  | Herman Adriaan van Karnebeek | 1921–1922 |
 Chile |  | Agustín Edwards | 1922–1923 |
 Cuba |  | Cosme de la Torriente y Peraza | 1923–1924 |
 Switzerland |  | Giuseppe Motta | 1924–1925 |
 Canada |  | Raoul Dandurand | 1925–1926 |
 Portugal |  | Afonso Costa | 1926 |
 Kingdom of Yugoslavia |  | Momčilo Ninčić | 1926–1927 |
 Uruguay |  | Alberto Guani | 1927–1928 |
 Denmark |  | Herluf Zahle | 1928–1929 |
 El Salvador |  | José Gustavo Guerrero | 1929–1930 |
 Kingdom of Romania |  | Nicolae Titulescu | 1930–1932 |
| Belgium | | Paul Hymans 2nd time | 1932–1933 |
 Union of South Africa |  | Charles Theodore Te Water | 1933–1934 |
 Sweden |  | Rickard Sandler | 1934 |
 Mexico |  | Francisco Castillo Nájera | 1934–1935 |
 Czechoslovakia |  | Edvard Beneš | 1935–1936 |
| Argentina |  | Carlos Saavedra Lamas | 1936–1937 |
 Turkey |  | Tevfik Rüştü Aras | 1937–1937 |
 British Raj |  | Sir Sultan Muhammed Shah, Aga Khan III | 1937–1938 |
| Ireland |  | Éamon de Valera | 1938–1939 |
 Norway |  | C. J. Hambro | 1939–1946 |
