Frederick II, Frederik II or Friedrich II may refer to:

• Frederick II, Holy Roman Emperor (1194–1250), King of Sicily from 1198; Holy Roman Emperor from 1220
• Frederick II of Denmark (1534–1588), king of Denmark and Norway 1559–1588
• Frederick II of Prussia (1712–1786), king 1740–1786, better known as Frederick the Great
• Frederick II, Grand Duke of Baden (1857–1928)
• Frederick II, Elector of Saxony (1412–1464)
• Frederick II, Elector of Brandenburg (1413–1471), margrave 1440–1470
• Frederick II, Elector Palatine (1482–1556), elector 1544–1556
• Frederick II (Archbishop of Cologne) (1120–1158)
• Frederick II, Duke of Upper Lorraine (995–1026), count of Bar and duke of Lorraine, co-reigning with his father from 1019
• Frederick II, Duke of Swabia (1090–1147)
• Frederick II, Duke of Lorraine (died 1213)
• Frederick II, Duke of Austria (died 1246), Duke of Austria 1230–1246
• Frederick II, Duke of Brunswick-Lüneburg (1418–1478)
• Frederick II, Duke of Holstein-Gottorp (1568–1587)
• Frederick II, Duke of Saxe-Gotha-Altenburg (1676–1732)
• Frederick II, Duke of Mecklenburg-Schwerin (1717–1785), called the Pious
• Friedrich II, Duke of Anhalt (1856–1918)
• Frederik II van Sierck (died 1322), bishop of Utrecht
• Frederick II, Margrave of Baden-Eberstein (died 1333)
• Frederick II, Margrave of Meissen (1310–1349)
• Frederick II, Marquess of Saluzzo (died 1396)
• Frederick II, Landgrave of Hesse-Homburg (1633–1708), hero of Heinrich von Kleist's play Der Prinz von Homburg
• Frederick II, Landgrave of Hesse-Kassel (1720–1785)
• Frederick II, Count of Diessen (1030–1075), bailiff of Regensburg cathedral
• Frederick II, Count of Celje (1379–1454), Ban of Croatia, Slavonia and Dalmatia
• Frederick II, Count of Vaudémont (1420s–1470), Lord of Joinville
• Frederick II Eugene, Duke of Württemberg (1732–1797)
• Frederick the Second, 1927 biography of Frederick II, Holy Roman Emperor, by Ernst Kantorowicz

• Frederik II Upper Secondary School in Fredrikstad, Norway, named for Frederick II of Denmark
• Frederick III of Sicily (1272–1337), the second Frederick to rule the kingdom
• Frederick Augustus II, Elector of Saxony (1696–1763) better known as King August III of Poland
• Frederick Augustus II of Saxony (1797–1854), king of Saxony 1836–1854
• Frederick Augustus II, Grand Duke of Oldenburg (1852–1931)
• Frederick Christian II, Duke of Schleswig-Holstein-Sonderburg-Augustenburg (1765–1814)
• Frederick Francis II, Grand Duke of Mecklenburg-Schwerin (1823–1883)
• Frederick William II (disambiguation)