Louis I may refer to:
Cardinals
Louis I, Cardinal of Guise (1527–1578)
Counts
Ludwig I, Count of Württemberg (c. 1098–1158) Louis I of Blois (1172–1205) Louis I of Flanders (1304–1346) Louis I of Châtillon (died 1346) Louis I, Count of Montpensier (1405–1486) Louis Günther I, Count of Schwarzburg-Rudolstadt (1581–1646)
Dukes
Louis I Wittelsbach, Duke of Bavaria (1173–1231) Louis I, Duke of Bourbon (1279–1342) Louis I, Duke of Orléans (1372–1407) Louis I, Duke of Bar (died in 1430) Louis I, Grand Duke of Hesse (1753–1830), previously Louis X, Landgrave of Hesse-Darmstadt
Kings Louis the Pious, Louis I of France, "the Pious" (778–840), king of France and Holy Roman Emperor Louis I of Hungary, Louis I of Poland and Hungary, (1326–1382) Louis I of Naples (1339–1384) Louis I of Spain (1707–1724) Louis I of Etruria (1773–1803) Louis Bonaparte (1778–1846), King of Holland 1806–1810 as Louis I Ludwig I of Bavaria (1786–1868) Luís I of Portugal (1838–1889) Louis VIII of France who claimed the throne of England as Louis I of England, (1216–1217) Louis X of France, also known as Louis I of Navarre (1289–1316) Louis Philippe I of France
Landgraves Louis I, Landgrave of Thuringia (ruled 1123–1140)
Princes
Louis I, Prince of Condé (1530–1569) Louis I, Prince of Monaco (1642–1701) Louis Frederick I, Prince of Schwarzburg-Rudolstadt (1667–1718)