Freiherr (German: [ˈfʁaɪˌhɛɐ̯]; male, abbreviated as Frhr.), Freifrau ([ˈfʁaɪˌfʁaʊ]; his wife, abbreviated as Frfr., lit. 'free lord' or 'free lady') and Freiin ([ˈfʁaɪ.ɪn], his unmarried daughters and maiden aunts) are designations used as titles of nobility in the German-speaking areas of the Holy Roman Empire, the Austro-Hungarian Empire and in its various successor states, including Austria, Prussia, Bavaria, Liechtenstein, Luxembourg, etc. Traditionally, it denotes the titled rank within the nobility above Ritter (knight) and Edler (nobility without a specific title) and below Graf (count or earl). The title superseded the earlier medieval form, Edelherr.

It corresponds approximately to the English baron in rank. The Duden orthography of the German language references the French nobility title of Baron, deriving from the Latin-Germanic combination liber baro (which also means "free lord"), as corresponding to the German "Freiherr"; and that Baron is a corresponding salutation for a Freiherr.

The title Freiherr derives from the historical situation in which an owner held free (allodial) title to his land, as opposed "unmittelbar" ("unintermediated"), or held without any intermediate feudal tenure; or unlike the ordinary baron, who was originally a knight (Ritter) in vassalage to a higher lord or sovereign, unlike medieval German ministerials, who were bound to provide administrative services for a lord. A Freiherr sometimes exercised hereditary administrative and judicial prerogatives over those resident in his barony instead of the liege lord, who might be the duke (Herzog) or count (Graf).

The German-language title of Freiherr is rendered in English as "Baron", although the title was derived separately in the two languages. Even in German, a Freiherr is often styled as and addressed by the more elegant, Latin equivalent "Baron" in social circumstances, although not the official title.

Separately, in the 19th century some families of the Baltic German nobility who had historically carried the title of Freiherr were recognized by the Tsardom of Russia as noble in the form of ukases additionally awarding the equivalent Russian title of Baron. When in 1919 privileges to members of dynastic and noble families were abolished by the constitution of the Weimar Republic and hence titles became part of the last name some members of the affected families chose to be officially named Freiherr while others preferred Baron to emphasize their Baltic-German heritage. This is why members of the same family can have different official last names.

The original distinction from other barons was that a Freiherr's landed property was allodial instead of a fief.

Barons who received their title from the Holy Roman Emperor are sometimes known as "Barons of the Holy Roman Empire" (Reichsfreiherren), in order to distinguish them from other barons, although the title as such was simply Freiherr. After the dissolution of the Holy Roman Empire in 1806, Reichsfreiherren did not belong to the noble hierarchy of any realm, but by a decision of the Congress of Vienna in 1815, their titles were nonetheless officially recognised. From 1806 the then independent German monarchies, such as Bavaria, Württemberg and Lippe could create their own nobility, including Freiherren (although the Elector of Brandenburg had, as king of the originally exclusively extraterritorial Prussia even before that date, arrogated to himself the prerogative of ennoblement). Some of the older baronial families began to use Reichsfreiherr in formal contexts to distinguish themselves from the new classes of barons created by monarchs of lesser stature than the Holy Roman Emperors, and this usage is far from obsolete.

As with most titles and designations within the nobility in the German-speaking areas of Europe, the rank was normally hereditary and would generally be used together with the nobiliary particle of von or zu (sometimes both: von und zu) before a family name.