* David Lloyd George (United Kingdom)
* Georges Clemenceau (France)
* Woodrow Wilson (United States)
* Vittorio Emanuele Orlando (Italy)
* Tsar Nicholas II (Russia) (until March 1917)
* Alexander Kerensky (Russia) (March-November 1917)
* Vladimir Lenin (Russia) (November 1917-March 1918)
* Leon Trotsky (Russia) (November 1917-March 1918)
Central Powers
* Kaiser Wilhelm II (Germany)
* Franz Joseph I (Austria-Hungary) (until November 1916)
* Charles I (Austria-Hungary) (November 1916-November 1918)
* Enver Pasha (Ottoman Empire)
* Ferdinand I (Bulgaria)