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 of Valois, 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)

Landgraves

  • Louis I, Landgrave of Thuringia (ruled 1123–1140)

Princes

  • Louis I de Bourbon, Prince de Condé (1530–1569)
  • Louis I, Prince of Monaco (1642–1701)
  • Louis Frederick I, Prince of Schwarzburg-Rudolstadt (1667–1718)