Ottoman Algeria, formally the Regency of Algiers, is an Ottoman territory centered on Algiers, eventually covering all coastal lands of modern Algeria.

It is established in 1525 when Hayreddin Barbarossa captures the city.

The Regency of Algiers is the principal center of Ottoman power in the Maghreb.

It is also a base from which attacks are made on European shipping.

It rivals and displaces the Ziyanids, the Hafsids and the Spanish possessions in northern Africa, and is a major hub of Mediterranean piracy and slave markets, until the French conquest of Algeria in 1830.