The Barbary corsairs, Barbary pirates, Ottoman corsairs, or naval mujahideen (in Muslim sources) were mainly Muslim corsairs and privateers who operated from the North African coast, known in Europe as the Barbary Coast, in reference to the Berbers. Slaves in Barbary could be of many ethnicities, and of many different religions, such as Christian, Jewish, or Muslim. Their predation extended throughout the Mediterranean, south along West Africa's Atlantic seaboard and into the North Atlantic as far north as Iceland, but they primarily operated in the western Mediterranean. In addition to seizing merchant ships, they engaged in razzias, raids on European coastal towns and villages, mainly in Italy, France, Spain, and Portugal, but also in Britain and Ireland, and Iceland (commemorated as the Turkish Abductions).

While such raids began after the Muslim conquest of the Iberian Peninsula in the 710s, the terms "Barbary pirates" and "Barbary corsairs" are normally applied to the raiders active from the 16th century onwards, when the frequency and range of the slavers' attacks increased. In that period, Algiers, Tunis and Tripoli came under the sovereignty of the Ottoman Empire, either as directly administered provinces or as autonomous dependencies known as the Barbary states. Similar raids were undertaken from Salé (see Salé Rovers) and other ports in Morocco.

The raids were such a problem that coastal settlements were seldom undertaken until the 19th century. Between 1580 and 1680, corsairs were said to have captured about 850,000 people as slaves and from 1530 to 1780 as many as 1.25 million people were enslaved. However, these numbers are estimated and provided by only one historian, Robert Davis, and have been questioned by others like David Earle. Some of these corsairs were European outcasts and converts (renegade) such as John Ward and Zymen Danseker. Hayreddin Barbarossa and Oruç Reis, the Turkish Barbarossa brothers, who took control of Algiers on behalf of the Ottomans in the early 16th century, were also notorious corsairs. The European pirates brought advanced sailing and shipbuilding techniques to the Barbary Coast around 1600, which enabled the corsairs to extend their activities into the Atlantic Ocean. The effects of the Barbary raids peaked in the early-to-mid-17th century.

Long after Europeans had abandoned oar-driven vessels in favor of sailing ships carrying tons of powerful cannon, many Barbary warships were galleys carrying a hundred or more fighting men armed with cutlasses and small arms. The Barbary navies were not battle fleets. When they sighted a European frigate, they fled.

The scope of corsair activity began to diminish in the latter part of the 17th century, as the more powerful European navies started to compel the Barbary states to make peace and cease attacking their shipping. However, the ships and coasts of Christian states without such effective protection continued to suffer until the early 19th century. Between 1801 and 1815, occasional incidents occurred, including two Barbary Wars waged by the United States, Sweden and the Kingdom of Sicily against the Barbary states. Following the Napoleonic Wars and the Congress of Vienna in 1814–15, European powers agreed upon the need to suppress the Barbary corsairs entirely. The remainder of the threat was finally subdued for Europeans by the French conquest of Algeria in 1830 and continuous campaigns and colonization by the French during the mid-to-late 19th century.

The Barbary corsairs were active from medieval times to the 1800s.

Both Europeans (e.g., the Dum Diversas) and Muslims considered themselves to be waging holy wars against each other during this era. European and American historical sources bluntly consider these operations to be a form of piracy and that their goal was mainly to seize ships to obtain spoils, money, and slaves. Muslim sources, however, sometimes refer to the "Islamic naval jihad"—casting the conflicts as part of a sacred mission of war under Allah, differing from the more familiar form of jihad only in being waged at sea. Accounts of Andalusian Muslims being persecuted by the Spanish Inquisition—willingly abetted by the Catholic Monarchs of Spain, who (though inaugurating what would later become Spain's "Golden Age") were initially faced with the post-Reconquista necessity of binding their (hitherto-divided) territories together, and hence adopted a militantly Christian national identity—provided more than enough justification, in Muslim eyes.

In 1198, the problem of Barbary piracy and slave-taking was so significant that the Trinitarians, a religious order, was founded to collect ransoms and even to exchange themselves as a ransom for those captured and pressed into slavery in North Africa. In the 14th century, Tunisian corsairs became enough of a threat to provoke a Franco-Genoese attack on Mahdia in 1390 (also known as the "Barbary Crusade"). Moorish exiles of the Reconquista and Maghreb pirates added to the numbers, but it was not until the expansion of the Ottoman Empire and the arrival of the privateer and admiral Kemal Reis in 1487 that the Barbary corsairs became a true menace to shipping from European Christian nations.