Frederick III may refer to:
- Frederick III of Sicily (self-styled), also known as King Frederick II of Sicily, (1272–1337)
- Frederick III of Germany or Frederick the Fair, King of the Romans and previously Duke Frederick I of Austria, (1289–1330)
- Frederick III the Simple, king of Sicily, (1341–1377)
- Frederick III, Holy Roman Emperor, (1415–1493)
- Frederick III, Duke of Brunswick-Lüneburg, (1424-1495)
- Frederick III, Elector of Saxony, (1463–1525)
- Frederick III, Elector Palatine, (1515–1576)
- Frederick III, Duke of Holstein-Gottorp, (1597–1659)
- Frederick III of Denmark, (1609–1670)
- Frederick III of Brandenburg or Frederick I of Prussia, Elector of Brandenburg, (1657–1713)
- Frederick III, Duke of Saxe-Gotha-Altenburg, (1699-1772)
- Frederick III, German Emperor, (1831–1888)
Famous quotes containing the words frederick and/or iii:
“Up rose old Barbara Frietchie then,
Bowed with her fourscore years and ten;
Bravest of all in Frederick town,
She took up the flag the men hauled down;”
—John Greenleaf Whittier (1807–1892)
“The army is the true nobility of our country.”
—Napoleon Bonaparte III (1808–1873)