Walī (Arabic: ولي, plural ʾawliyāʾ أولياء), is an Arabic word with a number of meanings, including "custodian", "protector", "helper", "a man close to God", or "holy man", etc. "Wali" is someone who has "Walayah" (authority or guardianship) over somebody else, and in fiqh (Islamic jurisprudence) particularly "an authorized agent of the bride in concluding a marriage contract (Islamic Law)", where the Wali traditionally selects the bride groom.
In some far-right Muslim countries, such as Saudi Arabia, the practice of forbidding girls and women from traveling, conducting official business, or undergoing certain medical procedures without permission from their male guardian continues to the present day.
Muslim scholars have held that in order for the nikah (marriage) to be valid, there must be consent of the bride, the groom and the bride's wali or male guardian. This view is held by most Muslim scholars, but the Hanafis hold that the wali's permission is not necessary for the nikah. The wali is typically the father or, failing that, a paternal grandfather or brother of the bride. Typically a father, brother or husband (a mahram) or paternal grandfather is wali mujbir, or if there is no Muslim relative, a qadi may function as wali. An order of succession of various male relatives is often spelled out by jurists. An example is this list written by Ibn Abd al-Wahhab: if the father is otherwise unavailable, guardianship should be assigned
first to the woman's brother, then to the paternal grandfather than to the woman's son.... [then it] passes to the tribe of the brother, unless it is law/base/despicable, ... [then the] paternal uncle takes over, followed by his son, then other relatives in paternal relationships. ... Maternal relative only have a claim to marriage guardianship if there are not paternal relatives. ... the sultan or political leader may serve as the marriage guardian ... only if he is a just man .... Thus the critical factor in selecting an alternative marriage guardian is the man's adherence to justice, not his political position.