Kaiser is a surname derived from the German imperial title Kaiser (English: emperor). The title Kaiser is in turn derived from the Latin title Caesar, which again is a derivation from the personal name of a branch of the gens (clan) Julia, to which belonged Gaius Julius Caesar, the forebear of the first Roman imperial family. The further etymology is unclear.
The name is not especially frequent (ca. 0.05% in Germany), but it is still ranked 41st in Germany as of 2000). Regions in Germany where it is more frequent are central Germany and the southern half of the Black Forest area, and to a lesser extent Southern Germany. It is also used in Austria and the Czech Republic.
Other names with the same origin are Kayser and Keiser; Keyser is more common as a Dutch spelling, and Qaisar is an Arabic version.