Swiss politician who became the first burgomaster, and virtual dictator, of Zürich, and whose struggles to maintain personal power ultimately brought the city into the Swiss Confederation (1351).

Although a member of the old Zürich nobility, Brun put himself at the head of a coalition of discontented knights and artisans that in 1336 overthrew the old oligarchical constitution. He drew up a new one, reorganized the governmental machinery of the city, and created the office of burgomaster, to which position he received title for life. Brun's attempts to eliminate all partisans of the old order, however, led to their continued opposition in exile under the patronage of the counts of Rapperswil, a branch of the House of Habsburg. Subsequent hostilities against Rapperswil (1337, 1350) eventually widened into war with Austria (September 1350); and, in seeking support against the Habsburgs, Zürich entered into permanent alliance with the Waldstätten, the forerunner of the Swiss Confederation (May 1, 1351). Brun's attitude toward this attachment, however, was marked by opportunism; and with the close of the Austrian war (1355), he attempted to reestablish the traditional good relations between the Habsburgs and Zürich at the expense of its new confederates. He died a pensioner of the Habsburgs.