Archduke (Ger. Erzlierzog), a German title in use from very early times. We find among the Franks archdukes of Austrasia. The title also existed in Lorraine and Brabant, and was especially assumed by the house of Austria, though there is no positive historical record as to when or why it was granted to them by the emperors. The Kahleberg branch of the house of Austria or Hapsburg has used the title since 1150, but without special privileges.

It became hereditary in that line after the promulgation of the golden bull, but the electors did not recognize its validity till 1453. It is supposed, however, that Maximilian I. extended this dignity to his branch of the family, attaching to it various privileges, and placing the archdukes in every respect above all other crowned vassals of the German empire. The Hapsburgs have preserved it ever since; and since the assumption by the emperor Francis of the title of emperor of Austria (1804), all the male and female members of that house have been called archdukes or archduchesses.