Charles I may refer to:

• Charlemagne (742–814), numbered Charles I in the lists of Holy Roman Emperors and French kings
• Charles I of Anjou (1226–1285), also king of Albania, Jerusalem, Naples and Sicily
• Charles I of Hungary (1288–1342), also king of Croatia
• Charles I of Navarre (1294–1328), also Charles IV of France
• Charles I of Bohemia (1316–1378), also Charles IV, Holy Roman Emperor
• Charles I of Norway (1408–1470), also Charles VIII of Sweden
• Charles I of Spain (1500–1558), also Charles V, Holy Roman Emperor
• Charles I of England, Scotland, and Ireland (1600–1649)
• Charles I of Württemberg (1823–1891)
• Charles I of Romania or Carol I (1839–1914)
• Charles I of Portugal or Carlos I (1863–1908)
• Charles I of Austria or Karl I (1887–1922), also Charles IV of Hungary and Charles III of Bohemia

• Charles I, Duke of Lorraine (953–993)
• Charles I, Count of Flanders (1083–1127/86–1127), called Charles the Good
• Charles, Count 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, Count of Armagnac (1425–1497)
• Charles I, Count of Ligny (1448–1530)
• Charles I, Duke of Savoy (1468–1490), titular king of Cyprus, Jerusalem, and Armenia
• Charles I, Duke of Münsterberg-Oels (1476–1536)
• Charles I, Duke of Mecklenburg (1540–1610)
• Charles I, Duke of Elbeuf (1556–1605)
• Charles I, Count Palatine of Zweibrücken-Birkenfeld (1560–1600)
• Charles I, Duke of Mantua and Montferrat or Charles Gonzaga (1580–1637)
• Charles I Louis, Elector Palatine (1617–1680)
• Charles I, Landgrave of Hesse-Kassel (1654–1730)
• Charles I, Landgrave of Hesse-Philippsthal (1682–1770)
• Charles I, Duke of Brunswick-Wolfenbüttel (1713–1780)
• Charles I, Duke of Parma (1716–1788), also Charles III of Spain and Sicily and Charles VII of Naples
• Charles Emmanuel I, Duke of Savoy (1562–1630)

• Charles I in Three Positions, an oil painting of Charles I of England by Sir Anthony van Dyck (1635 or 1636)
• King Charles I (play), a 1737 play by William Havard
• Charles the First (play), an 1834 tragedy by Mary Russell Mitford
• Charles the First (Basquiat), by American artist Jean-Michel Basquiat

• Carl I (disambiguation)