In medieval military orders such as the Knights Templar or the Livonian Brothers of the Sword, the Grand Master was the formal and executive head of a military and feudal hierarchy, which can be considered a "state within the state", especially in the crusader context lato sensu, notably aimed at the Holy Land or pagan territories in Eastern Europe, as well as the reconquista in the Iberian peninsula.
If an order is granted statehood and thus widely considered sovereign, the Grand Master is also its Head of State. If within the Holy Roman Empire, a Reichsfürst and Head of Government, and thus a true territorial Prince of the church, as was the case with the Teutonic Knights and the Sovereign Military Order of Malta.
Except the modern continuation of the organisations of medieval foundation, the title of Grand Master has been used by the heads of Grand Lodges of Freemasons since 1717, and by Odd Fellows since the 18th century.
The title of Grand Master is also used by various other fraternities, including academic ones associated with universities. The national leader of the Kappa Sigma Fraternity goes by the title "Worthy Grand Master". The heads of local chapters use the title of "Grand Master".