Führer (/ˈfjʊərər/ FURE-ər [ˈfyːʁɐ] ^ⓘ, spelled Fuehrer when the umlaut is unavailable) is a German word meaning 'leader' or 'guide'. As a political title, it is strongly associated with Adolf Hitler, the dictator of Nazi Germany from 1933 to 1945. Hitler officially called himself der Führer und Reichskanzler ('the Leader and Chancellor of the Reich') after the death of President Paul von Hindenburg in 1934, as well as the subsequent merging of the offices of Reichspräsident and Reichskanzler.

Nazi Germany cultivated the Führerprinzip ('leader principle'), and Hitler was generally known as simply der Führer ('the Leader').

In compound words, the use of Führer remains common in German and is used in words such as Reiseführer ('travel guide'), Museumsführer ('museum docent'), Bergführer ('mountain guide') and Oppositionsführer ('leader of the opposition'). However, because of its strong association with Hitler, the isolated word itself usually has negative connotations when used with the meaning of leader, especially in political contexts.

The word Führer has cognates in the Scandinavian languages, spelled fører in Danish and Norwegian. In Norwegian, the word has the same meaning as the German word. The Norwegian word for mayor is ordfører, literally meaning word leader. In Swedish Ordförande means 'Chairman' and applies to a wide range of situations, for example in corporate boards or as the head of an official gathering of members. In Swedish and Danish, förare and fører normally means 'driver' (of a vehicle), a meaning Führer can also have in German. However, in the compound word härförare and hærfører, that part does mean 'leader', and is a cognate of the German Heerführer (military leader).

Führer has been used as a military title (compare Latin Dux) in Germany since at least the 18th century. The usage of the term "Führer" in the context of a company-sized military subunit in the German Army referred to a commander lacking the qualifications for permanent command. For example, the commanding officer of a company was titled "Kompaniechef" (lit. 'Company Chief'), but if he did not have the requisite rank or experience, or was only temporarily assigned to command, he was officially titled "Kompanieführer". Thus operational commands of various military echelons were typically referred to by their formation title followed by the title Führer, in connection with mission-type tactics used by the German military forces. The term Führer was also used at lower levels, regardless of experience.

The first example of the political use of Führer was with the pan-German Austrian Georg Ritter von Schönerer (1842–1921), a major exponent of pan-Germanism and German nationalism in Austria, whose followers commonly referred to him as the Führer, and who also used the Roman salute – where the right arm and hand are held rigidly outstretched – which they called the "German greeting". According to historian Richard J. Evans, this use of "Führer" by Schönerer's Pan-German Association, probably introduced the term to the German far-right, but its specific adoption by the Nazis may also have been influenced by the use in Italy of "Duce", also meaning "leader", as an informal title for Benito Mussolini, the Fascist Prime Minister, and later (from 1922) dictator, of that country.

Adolf Hitler took the title to denote his function as head of the Nazi Party; he received it in 1921 when, infuriated over party founder Anton Drexler's plan to merge with another antisemitic far-right nationalist party, he resigned from the party. Drexler and the party's Executive Committee then acquiesced to Hitler's demand to be made the chairman of the party with "dictatorial powers" as the condition for his return.

In 1933, Hitler was appointed Reichskanzler (Chancellor of the Reich) by President Paul von Hindenburg.