During the Middle Ages, an advocatus (sometimes given as modern English: advocate; German: Vogt; French: avoué) was an office-holder who was legally delegated to perform some of the secular responsibilities of a major feudal lord, or for an institution such as an abbey. Many such positions developed, especially in the Holy Roman Empire. Typically, these evolved to include responsibility for aspects of the daily management of agricultural lands, villages and cities. In some regions, advocates were governors of large provinces, sometimes distinguished by terms such as Landvogt (in German).

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 in the secular world, but were also responsible for exercising lordly responsibilities within the church's lands, such as the handling of legal cases which might require the use of a death penalty. The positions of these office-holders eventually came to be seen as inheritable titles themselves, with their own feudal privileges connected to them.

The advocatus as an officer of a court of law first appeared in the 12th and 13th centuries, concomitant with the rediscovery of Roman law.