Louis IX, Landgrave of Hesse-Darmstadt

Louis IX of Hesse-Darmstadt (Ludwig) (15 December 1719 – 6 April 1790) was Landgrave of Hesse-Darmstadt from 1768 to 1790.

Overview
Louis IX was a son of Louis VIII, Landgrave of Hesse-Darmstadt, and Charlotte of Hanau-Lichtenberg and Müntzenberg.

He was born in Darmstadt on 15 December 1719. On 12 August 1741, Louis married Caroline, daughter of Christian III, Duke of Zweibrücken. They had three sons and five daughters, including:


 * Princess Caroline of Hesse-Darmstadt (1746–1821), married Frederick V, Landgrave of Hesse-Homburg
 * Princess Frederica Louisa of Hesse-Darmstadt (1751–1805), married King Friedrich Wilhelm II of Prussia and became Queen of Prussia
 * Prince Louis X (1753–1830), later Grand Duke Louis I, married his first cousin Princess Louise of Hesse-Darmstadt
 * Princess Amalie of Hesse-Darmstadt (1754–1832), married her first cousin Karl Ludwig, Hereditary Prince of Baden
 * Princess Wilhelmina Louisa of Hessen-Darmstadt (1755–1776), married Grand Duke Pavel Petrovich of Russia, later emperor
 * Princess Luise Auguste of Hesse-Darmstadt (1757–1830), married Karl August, Grand Duke of Saxe-Weimar-Eisenach
 * Prince Frederick (1759–1802)
 * Prince Christian of Hesse-Darmstadt (1763–1830)
 * A stillborn son on 3 May 1742

In 1775, Louis IX married Marie Adelaide of Cheirouze, countess of Lemberg. On 6 April 1790, Louis died in Pirmasens.

Louis IX and his first wife became the most recent common ancestors of all current sovereigns of hereditary monarchies in Europe in 2022 after Charles III became King of the United Kingdom.

Royal descendants
Dotted lines indicate marriage.