| Country | Sovereign | Born | Acceded | Consort (born) | Heir (born) |
 Kingdom of the Netherlands |
 Queen Wilhelmina | 31 Aug 1880 | 23 Nov 1890 |  Princess Juliana (1909) | |
 Kingdom of Italy |  King Victor Emanuel III | 11 Nov 1869 | 29 Jul 1900 |  Queen Elena (1873) |  Crown Prince Umberto (1904) |
 Kingdom of Norway |  King Haakon VII | 3 Aug 1872 | 18 Nov 1905 |  Queen Maud (1869) |  Crown Prince Olav (1903) |
 Kingdom of Sweden |  King Gustaf V | 16 Jun 1858 | 8 Dec 1907 |  Crown Prince Gustaf Adolf (1882) | |
 United Kingdom of Great Britain and Northern Ireland Irish Free State |  King George V | 3 Jun 1865 | 6 May 1910 |  Queen Mary (1867) |  Prince Edward, Prince of Wales (1894) |
 Kingdom of Denmark Kingdom of Iceland |  King Christian X | 26 Sep 1870 | 14 May 1912 |  Queen Alexandrine (1879) |  Crown Prince Frederik (1899) |
 Kingdom of Bulgaria |  King Boris III | 30 Jan 1894 | 3 Oct 1918 |  Queen Ioanna (1907) |  Prince Kyril (1895) |
 Grand Duchy of Luxembourg |  Grand Duchess Charlotte | 23 Jan 1896 | 14 Jan 1919 |  Prince Felix (1893) |  Her. Grand Duke Jean (1921) |
 Kingdom of Hungary |  Miklós Horthy, Regent | 18 Jun 1868 | 1 Mar 1920 | ||
 Vatican City (11 Feb 1929) |  Pope Pius XI | 31 May 1857 | 6 Feb 1922 | ||
 Principality of Monaco |  Prince Louis II | 12 Jul 1870 | 27 Jun 1922 |  Her. Princess Charlotte (1898) | |
 Kingdom of Albania |  King Zog | 9 Oct 1895 | 1 Sep 1928 |  Tati Kryeziu, Prince of Kosovo (1923) | |
 Principality of Liechtenstein |  Prince Franz I | 28 Aug 1853 | 11 Feb 1929 |  Prince Franz Joseph (1906) | |
 Kingdom of Romania |  King Carol II | 15 Oct 1893 | 8 Jun 1930 |  Crown Prince Michael (1921) | |
 Kingdom of Belgium |  King Leopold III | 3 Nov 1901 | 23 Feb 1934 |  Queen Astrid (1905) |  Prince Baudouin, Duke of Brabant (1930) |
 Kingdom of Yugoslavia |  King Peter II | 6 Sep 1923 | 9 Oct 1934 |  Prince Tomislav (1928) |
