Köprülü (köprülü´), family of humble Albanian origin, several members of which served as grand vizier (chief executive officer) in the Ottoman Empire. The name is also spelled Kiuprili, Koprili, and Kuprili. Mehmed Köprülü, 1583–1661, became grand vizier of Muhammad IV in 1656. He reorganized the Ottoman fleet, conquered (1658) Transylvania, restored internal order (by executing dissidents), reformed the finances, and built forts along the Don and Dnieper rivers. During his vizierate the Ottoman Empire regained some of its former prestige and vitality. He was succeeded as vizier by his son Ahmed Köprülü, 1635–76. An able statesman and soldier, he took (1669) the last Venetian stronghold in Crete, but he was severely defeated (1664) by Montecucculi at Szentgotthárd in Hungary and suffered reverses in his campaigns against John III of Poland. Ahmed was succeeded as vizier by Kara Mustafa, his brother-in-law. Ahmed's brother, Mustafa Köprülü, 1637–91, became vizier in 1689, at a time when the Austrians and their allies were advancing victoriously into the Ottoman Empire. He continued his predecessors' administrative and fiscal reforms and improved the status of the Christian subjects. He drove the Austrians from Serbia but was killed in the battle of Slankamen. His cousin, Hüseyin Köprülü, d. 1702, became vizier after the Turkish defeat at Senta in 1697. Recognizing the exhaustion of Turkey, he negotiated a humiliating peace (see Karlowitz, Treaty of). He too was a reformer and patronized the arts and letters. Mustafa Köprülü's son, Numan Köprülü, d.1719, was vizier in 1710–11. Another son, Abdullah Köprülü, d. 1735, was acting vizier from 1723 until his death.