Ottoman sultan from 1695 to 1703, whose determination to regain territories lost after the unsuccessful attempt to take Vienna in 1683 led to the continuation of the war against the Holy League (Austria, Poland, and Venice).

Mustafa's military campaigns met with early success. After recovering the island of Chios from Venice, he made gains against Austria in 1695 and 1696. The Russians occupied Azov (at the mouth of the Don River) in 1696, however, and he was defeated by the Austrians at Senta (see Zenta, Battle of) in 1697. The Treaty of Carlowitz (Carlowitz, Treaty of) (1699) radically reduced Turkey's Balkan holdings, and the Treaty of Constantinople (1700) confirmed Russia's gains.

Internally, the continued warfare caused social and economic dislocations. Heavy taxes drove many cultivators off the land; and the government's exclusive preoccupation with Europe resulted in local revolts in eastern Anatolia and among the Arab tribes of Syria and Iraq. Disillusioned by the defeat at Senta, Mustafa left most matters of state to the leader of the Muslim hierarchy, Feyzullah, while he himself devoted his last years to hunting. A military mutiny deposed Mustafa on Aug. 22, 1703.