Grand Rabbi

Chief Rabbi is a title given in several countries to the recognised religious leader of that country's Jewish community, or to a rabbinic leader appointed by the local secular authorities. Since 1911, through a capitulation by Rabbi Ben-Zion Meir Hai Uziel, Israel has had two chief rabbis, one Ashkenazi and one Sephardi.

Cities with large Jewish communities may also have their own chief rabbis; this is especially the case in Israel but has also been past practice in major Jewish centers in Europe prior to the Holocaust. North American cities rarely have chief rabbis. One exception however is Montreal, with two—one for the Ashkenazi community, the other for the Sephardi.

The Chief Rabbi's name is often followed by ABD, which stands for Av Beit Din.

Jewish law provides no support for the post of a "chief rabbi" since every rabbi has equal authority in principle. The position arose in Europe in the Middle Ages from governing authorities largely for secular administrative reasons such as collecting taxes and registering vital statistics, and for providing an intermediary between the government and the Jewish community, for example in the establishment of the Crown rabbi in several kingdoms of the Iberian Peninsula, the rab de la corte in Kingdom of Castile or the arrabi mor in Kingdom of Portugal, likely influenced by the expectations of their Catholic, Orthodox, and Anglican governments and neighbors. Similarly, in the 19th century there was a Crown rabbi of the Russian Empire.

The appointment of a new Chief Rabbi of Ireland has been put on hold since 2008.

The position of chief rabbi of the Land of Israel has existed for hundreds of years. During the mandatory period, the British recognized the chief Rabbis of the Ashkenazi and Sephardi communities, just as they recognized the Mufti of Jerusalem. The offices continued after statehood was achieved. Haredi Jewish groups (such as Edah HaChareidis) do not recognize the authority of the Chief Rabbinate. They usually have their own rabbis who do not have any connection to the state rabbinate.

...
Wikipedia