Title: Marriage officiant
Content:   A marriage officiant is a person who officiates at a wedding ceremony. Religious weddings, such as Christian ones, are officiated by a pastor, such as a priest or vicar. Similarly, Jewish weddings are presided over by a rabbi, and in Islamic weddings, an imam is the marriage officiant. In Hindu weddings, a pandit is the marriage officiant. Some non-religious couples get married by a minister of religion, while others get married by a government official, such as a civil celebrant, judge, mayor, or Justice of the peace.
Title: Marriage officiant
Content:  In the United States, a marriage officiant is a civil officer such as a justice of the peace who performs acts of marriage or civil union. Their main responsibility is to witness the consent of the intended spouses for the wedding license and hence validate the marriage or civil union for legal purposes.
Title: Officiant
Content:  An officiant is someone who officiates (i.e. leads) at a service or ceremony, such as marriage, burial, or namegiving/baptism. Religious officiants are usually ordained by a religious denomination as members of the clergy. Some officiants work within congregations in some denominations and for specified ceremonies (e.g. funerals), as non-ordained members on the clergy team. Clergy/officiants differ from chaplains in that the clergy serve the members of their congregation, while chaplains are usually employed by an institution such as the military, a hospital or other health care facility, etc. There may be more than one con-celebrant, but, even when a higher-ranking cleric is present, (save the Pope), there is only one principal celebrant. Secular officiants include civil celebrants, Humanist Society–appointed officiants,  Justices of the Peace,  marriage commissioners, notaries, and other persons empowered by law to perform legal marriage ceremonies. Many secular celebrants/officiants conduct the whole range of ceremonies which mark the milestones of human life.
Title: Wedding
Content: Bride: A woman about to be married. ; Bridegroom or Groom: A man about to be married. ; Marriage officiant: The person who officiates at the wedding, validating the wedding from a legal and/or religious standpoint. This person may be a judge, justice of the peace, or a member of the clergy. In Hindu marriages, the marriage officiant is called a pandit or Brahmin. ; Best Man, Woman, or Person: The chief assistant to a bridegroom at a wedding, typically a sibling or friend of special significance in his life. Often holds the wedding rings until their exchange. ; Mothers of a Bride or Groom ; Fathers of a Bride or Groom ; Maid, Matron 
Title: Marriage officiant
Content:  In Judaism, a Rabbi officiates Jewish weddings. However, the Rabbi's function is to ensure that the Jewish religious laws of the wedding ceremony are followed, particularly making sure that the Jewish witnesses are valid. The Rabbi traditionally recites the blessing for the ceremony on behalf of the groom, although in ancient times the groom would have recited this blessing.
Title: Marriage officiant
Content: Christianity: ; Catholic, Lutheran, Orthodox, Anglican - Priest ; Methodist, Moravian, Baptist, Reformed - Minister (Christianity) ; Other Faiths: ; Hindu - Pujari ; Islamic - Imam ; Jewish - Rabbi ; Mormon - Bishop Religious weddings are officiated by clergy people: The officiant's duties and responsibilities, as well as who may be an officiant vary among jurisdictions.
Title: Celebrant (Australia)
Content:  In Australia, celebrants are people who conduct formal ceremonies in the community, particularly weddings, which are the main ceremony of legal import conducted by celebrants. They may also conduct extra-legal ceremonies such as naming of babies, renewal of wedding vows, funerals, memorial services, Divorce, Becoming a teenager, support in adolescence, changing name, significant birthday, retirement, adopting a child, on taking over a house, on leaving a house, or dedicating a house - in short for all of life milestones. Officiating at a marriage, the flagship ceremony of every culture, requires that the celebrant be an authorised marriage celebrant under Australian law, or the law where the marriage takes place, but officiating at non legal ceremonies does not.
Title: Marriage officiant
Content:  In the United States, Canada and many other countries, marriages are legally performed by a member of the clergy, a public official (e.g.a judge), or where authorised, by a civil celebrant (e.g. New Jersey). Some celebrants perform same-sex weddings and commitment ceremonies. Laws in each state of the United States vary about who has the ability to perform wedding ceremonies, but celebrants or officiants are usually categorized as "clergy" and have the same rights and responsibilities as ordained clergy. There is some controversy over whether these laws promote religious privilege that is incompatible with the United States Constitution.
Title: Marriage officiant
Content:  Protestant weddings are conducted by a pastor such as a priest as with Lutheranism and Anglicanism, or a minister as with Methodism.
Title: Marriage officiant
Content:  In the Catholic Church, it is the bride and groom who perform the Sacrament of Matrimony (marriage), but a marriage can only be valid if the Church has a witness at the wedding ceremony whose function is to question the couple to ensure that they have no obstacle to marriage (such as an un-annulled previous marriage or certain undisclosed facts between the couple) and that they are freely choosing to wed each other. All ordained clergy (i.e. a deacon, priest, or bishop) may witness the wedding ceremony itself, though usually the wedding ceremony occurs during a Mass, which deacons lack the authority or ability to celebrate; however, in weddings that take place inside Mass, the deacon may still serve as the witness to the wedding, provided that a priest or bishop celebrates the Mass; and in weddings that take place outside Mass (which usually occurs in a marriage between a Catholic and a non-Christian or, less often, non-Catholic), the ceremony is the same for deacons, priests, and bishops (with few or no changes).

Question: what do you call a person who officiates a wedding?
Answer: vow master.
solemniser.
marriage officiant.
"vow master".