Kaiser is a German title meaning emperor, derived from the Roman title of Caesar, as is the Slavic title of Czar.

The Holy Roman Emperors (962 - 1806) (the "First German Reich") called themselves Kaiser; they saw their rule as a continuation of that of the Roman Emperors and so used the name "Caesar" to reflect their supposed heritage. The rulers of the Austro-Hungarian Empire (1806 - 1918) also used the title Kaiser. In English usage, however, the title is mainly associated with the emperors of the unified German Empire (1871 - 1918) (the "Second Reich").

There were three Kaisers of the German Empire. All belonged to the Hohenzollern dynasty, which had ruled Prussia before ascending to the German imperial throne. The three Kaisers were:

• Wilhelm I (1871 - 1888)
• Friedrich (1888)
• Wilhelm II (1888 - 1918)

See also: German Monarchy