The assassination of King Henri IV of France and arrest of his assassin François Ravaillac by Charles-Gustave Housez (1860); Credit – Wikipedia
This does not purport to be a complete list.
- Assassination of Edmund I, King of England (946)
- Assassination of Saint Edward the Martyr, King of England (978)
- Suspicious Death of William Rufus, King of England (1100)
- Death of Richard II, King of England (1400)
- Assassination of James I, King of Scots (1437)
- Assassination of Henry VI, King of England (1471)
- Execution of Lady Jane Grey, Queen of England (1553)
- Assassination of Willem I the Silent, Prince of Orange (1584)
- Execution of Mary, Queen of Scots (1587)
- Assassination of Henri III, King of France (1589)
- Assassination of Henri IV, King of France (1610)
- Execution of Charles I, King of England (1649)
- Assassination of Peter III, Emperor of All Russia (1762)
- Assassination of Ivan VI, deposed Emperor of All Russia (1764)
- Assassination of Gustav III, King of Sweden (1792)
- Executions of Louis XVI and Marie Antoinette, King and Queen of France (1793)
- Assassination of Paul I, Emperor of All Russia (1801)
- Execution of Maximilian I, Emperor of Mexico, Archduke of Austria (1867)
- Assassination of Alexander II, Emperor of All Russia (1881)
- Assassination of Empress Elisabeth of Austria (1898)
- Assassination of Umberto I, King of Italy (1900)
- Assassination of Alexander I, King of Serbia and Queen Draga (1903)
- Assassination of Carlos I, King of Portugal and Luís Filipe, Prince Royal (1908)
- Assassination of George I, King of Greece (1913)
- Assassination of Archduke Franz Ferdinand, Heir to the Throne of Austria-Hungary (1914)
- Execution of Grand Duke Michael Alexandrovich of Russia (1918)
- Execution of Nicholas II, Emperor of All Russia and His Family (1918)
- Execution of Grand Duchess Elizabeth Feodorovna of Russia & Five Other Romanovs (1918)
- Execution of Four Grand Dukes of Russia (1919)
- Assassination of Mohammed Nadir Shah, King of Afghanistan (1933)
- Assassination of Alexander I, King of Yugoslavia (1934)
- The Mysterious Death of Ananda Mahidol, King of Thailand (1946)
- Assassination of Abdullah I, King of Jordan (1951)
- Assassination of Faisal II, King of Iraq, members of his family, and palace staff (1958)
- Assassination of Faisal I, King of Saudi Arabia (1975)
- Assassination of King Birendra and Queen Aishwarya of Nepal and nine other members of the royal family (2001)