A vicar is a representative, deputy or substitute of the bishop. The title appears in a number of Christian ecclesiastical contexts, but also as an administrative title, or title modifier, in the Roman Empire. The Pope uses the title Vicarius Christi, meaning the vicar of Christ. The papacy first used this title in the 8th century; earlier they used the title „vicar of Saint Peter“ or vicarius principis apostolorum, the „vicar of the chief of the apostles“. On the other hand, Wilibrord (658–739) and Boniface (+754) made a new practice. First, Wilibrord made vicar bishops for him, so he had preached without administrative problems in his diocese. And after him, Boniface made two vicars. They were Anglo- Saxon in origin and made a new practice in the Church, in West.
In the early Christian churches, bishops likewise had their vicars, and also the rural bishops, the curate who had the cure or care of all the souls outside the episcopal cities. Vicars have various titles based on what role they are performing. In the West, an apostolic vicar is a bishop or priest who heads a missionary particular. Vicars exercise authority as the agents of the bishop of the diocese for one kind of office. Most vicars, however, have ordinary power, which means that their agency is not by virtue of a delegation but is established by law.