| Sovereign | Birthdate | Reign | Deathdate (if different) | |||
| Began | Ended | |||||
| Otto I | 1815 | 1832 | 1862 | 1867 | ||
| George I | 1845 | 1863 | 1913 | |||
| Constantine I | 1868 | 1913 | 1917 | 1923 | ||
| 1920 | 1922 | |||||
| Alexander I | 1893 | 1917 | 1920 | |||
| George II | 1890 | 1922 | 1924 | |||
| 1935 | 1947 | |||||
| Paul I | 1901 | 1947 | 1964 | |||
| Constantine II | 1940 | 1964 | 1974 | (living) |