Charles I may refer to:
In Kings and Emperors:
- Charles I, Holy Roman Emperor or Charlemagne (742–814)
- Charles I of Naples (1226–1285)
- Charles I of Hungary (1288–1342)
- Charles I of Bohemia (1316–1378)
- Charles I of Norway (1409–1470)
- Charles I of Spain (1500–1558)
- Charles I of England, Scotland, and Ireland (1600–1649)
- Charles I of Romania (1839–1914)
- Charles I of Portugal (1863–1908)
- Charles I of Austria (1887–1922)
In others:
- Charles, Duke of Lower Lorraine (953–993)
- Charles I, Count of Flanders (1080/86–1127), called Charles the Good
- Charles of Valois or Charles I, count of Alençon 1291–1325
- Charles I, Lord of Monaco (died 1357)
- Charles I, Duke of Bourbon (1401–1456)
- Charles I, Count of Nevers (1414–1464)
- Charles I, Margrave of Baden-Baden (died 1475)
- Charles I, Duke of Savoy (1482–1490)
- Charles I, Count Palatine of Zweibrücken-Birkenfeld (1560–1600)
- Charles I, Duke of Elbeuf (1556–1605)
- Charles I, Duke of Mantua and Montferrat (1580–1637)
- Charles I Louis, Elector Palatine (1617–1680)
- Charles I, Landgrave of Hesse-Kassel (1654–1730)
- Charles I, Duke of Brunswick-Wolfenbüttel (1713–1780)
- Charles I, Duke of Parma or Charles III of Spain