Pedro Lascuráin served as president of Mexico for less than one hour. The country’s 1857 constitution dictated that the line of succession to the presidency ran through the vice president, the attorney general, the foreign minister, and the interior minister. On Feb. 19, 1913, general Victoriano Huerta overthrew President Francisco Madero as well as his vice president and attorney general. To give his coup some appearance of legitimacy, he had foreign minister Lascuráin assume the presidency, appoint him interior minister, then resign. Lascuráin’s presidency is the shortest in world history.
Charles Brandon was Duke of Suffolk for one hour in 1551. He inherited the title when his elder brother Henry died of sweating sickness, then succumbed himself to the same disease, giving him the shortest tenure of a British peer.
Louis X of France died while his wife was pregnant, so that their son, John I, was born onto the throne. That makes him the youngest king in French history and the only person to have been king of France since birth. He lived only five days, so he’s also the only person to have held the French throne throughout his life. He’s remembered as “John the Posthumous.”