Cezayirli Gazi Hasan Pasha or Hasan Pasha of Algiers (1713 – 19 March 1790) was an Ottoman captain, Grand Admiral Kapudan Pasha (1770–90), Grand Vizier (1790), and general in the late 18th century.
He is known to have been bought as a Georgian slave in eastern Turkey by a Turkish merchant of Tekirdağ, who raised him in that city considering him on a par with his own sons.
He rose through the ranks of the Ottoman military hierarchy and was for a time with the Barbary Coast pirates based in Algiers (whence his name Cezayirli, meaning "from Algiers" in Turkish). He was a fleet commander during the Battle of Chesma aboard the Real Mustafa and was able to extract the forces under his command from the general disaster for the Turkish navy that occurred there. He arrived at the Ottoman capital with the bad news, but was highly praised for his own accomplishment and promoted, first to chief of staff and later to grand vizier. He dislodged the Russian fleet which had established a base on the Aegean island of Limni.
Anecdotal evidence indicates that, immediately after the defeat at Chesma, he and his men were lodged by a local priest in Ayvalık who did not know who they were. Hasan Pasha did not forget the kindness shown at that hour of crisis and later accorded virtual autonomy to the Greek-dominated town of Ayvalık, paving the way for its becoming an important cultural center for that community in the Ottoman Empire in the 19th century.
The defeat also prompted Hasan Pasha to establish the Naval Engineering Golden Horn Shipyard (later Turkish Naval Academy) in 1773.
Hasan Pasha blockaded Acre in the summer of 1775 in order to check the power of the autonomous Arab ruler of Palestine, Zahir al-Umar. Hasan Pasha ordered Zahir to pay 50,000 piasters to relieve the siege. Zahir ultimately refused and consequently, Hasan Pasha's ships bombarded Acre, but the Turks manning Acre's cannons refused Zahir's orders to fire back at the ships and intentionally directed their fire away from Hasan Pasha's naval forces. Their loyalty to the Ottoman sultan precluded them from firing on his military. Zahir fled, but was killed by Hasan Pasha's troops before he could escape.