An advocatus, sometimes simply advocate, Vogt (German, pronounced [foːkt] ^ⓘ), Fauth (Old High German) or avoué (French, pronounced [avwe] ^ⓘ), was a type of medieval office holder, particularly important in the Holy Roman Empire, who was delegated some of the powers and functions of a major feudal lord, or for an institution such as an abbey. They typically had responsibility for the "comital" functions which defined the office of early medieval "counts", such as taxation, recruitment of militias, and maintaining law and order. This type of office could apply to specific agricultural lands, villages, castles, and even cities. In some regions, advocates came to be governors of large provinces, sometimes distinguished by terms such as Landvogt.

In different parts of medieval Europe, the term advocate developed different meanings, and other terms were also sometimes used to represent similar offices. For example, Anglo-Norman comital functions for larger districts were executed by vicomtes in Normandy, and sheriffs in England. In contrast, the advocatus or advocate as an officer of a court of law, which is still current in modern English, first appeared in the 12th and 13th centuries, concomitant with the rediscovery of Roman law. The common thread which connects the different meanings of advocate is that someone is called upon to perform a function for others.

While the term was eventually used to refer to many types of governorship and advocacy, one of the earliest and most important types of advocatus was the church advocate (advocatus ecclesiae). These were originally lay lords, who not only helped defend religious institutions from violence, but were also responsible for exercising the comital or lordly responsibilities within the church's lands, such as the management of courts which could inflict a death penalty. In return they received an income from the lands, and the positions of these office-holders often came to be seen as inheritable titles themselves, with their own feudal privileges connected to them.

The terms used in various European languages derive from a general Latin term for any person called upon (Latin: ad vocatus) to speak for another.

Apart from the English terms advocate and advowee, German terms are sometimes mentioned in English accounts of the Holy Roman Empire, and these include Vogt (German: [foːkt], from Old High German, also Voigt or Fauth; plural Vögte). The territory or area of responsibility of a Vogt is called a Vogtei (from [ad]vocatia).

Related terms include Dutch: (land-) voogd; Danish: foged; Norwegian: fogd; Swedish: fogde; Polish: wójt; Finnish: vouti; Lithuanian: vaitas; and Romanian: voit.

Ecclesiastical advocates were specially bound to represent their lords by managing a court system, to protect law and order. They exercised civil jurisdiction in the domain of the church or monastery and were bound to protect the church with arms in the event of an actual assault. Finally, it was their duty to lead the men-at-arms in the name of the church or monastery, and to command them in time of war. In return for these services, the advocate received certain revenues from the possessions of the church in the form of supplies or services, which he could demand, or in the form of a lien on church property.

Such advocates were to be found even in Roman times; a Synod of Carthage decreed, in 401, that the emperor should be requested to provide, in conjunction with the bishops, defensores for the churches. There is evidence, moreover, for such defensores ecclesiæ in Italy, at the close of the fifth century, but Pope Gregory I confined the office to members of the clergy. It was the duty of these defensores to protect the poor and defend the rights and possessions of the church.