There were three rulers known as Frederick (German Friedrich) III of Germany:

• Frederick the Handsome, Duke of Austria from 1308 to 1330, who was elected as German King in the time of Louis the Bavarian (1326) as the result of a compromise between the Houses of Wittelsbach and Habsburg. In this function he is Frederick III of Germany. However, since he predeceased Louis, he never went on to rule as Emperor.
• Emperor Frederick III from the House of Habsburg (Frederick V as Archduke of Austria), who, as German King (elected in 1440), was crowned as Holy Roman Emperor Frederick III in 1452.
• Emperor Frederick III, from the House of Hohenzollern, King of Prussia and German Emperor only for a few months in 1888. Technically, he should have been Emperor Frederick I, and had considered taking the name "Frederick IV" to show his status as heir of the Holy Roman Emperors; but since the Hohenzollern Emperors were numbered in continuation of the Kings of Prussia, he is also remembered as Frederick III.