An exorcist is a person who performs exorcism, the ridding of demons or other supernatural beings who have possessed a person, or (sometimes) a building or other object.
Exorcists in various religions
Since the Council of Trent, "Exorcist" was one of the four minor orders in the ministry Roman Catholic Church, received after the tonsure. At the time this order was formally defined and confined exclusively to exorcism of the catechumen in the rite of Baptism, leaving exorcisms of demons to priests; but its role was later expanded. By the twentieth century, the order had become purely ceremonial. As a minor order, Exorcists wore the surplice. The office of Exorcist was not a part of the sacrament of Holy Orders but as a sacramental was instead first conferred on those who had the special charism to perform its duties and later to those studying for the priesthood.The Exorcist order was suppressed during the reforms of the minor orders after the Second Vatican Council