The Maghreb (; Arabic: الْمَغْرِب, romanized: al-Maghrib, lit. 'the west'), also known as the Arab Maghreb (Arabic: المغرب العربي) and Northwest Africa, is the western part of the Arab world. The region comprises western and central North Africa, including Algeria, Libya, Mauritania (also considered part of West Africa), Morocco, and Tunisia. The Maghreb also includes the disputed territory of Western Sahara (controlled mostly by Morocco and partly by the Sahrawi Arab Democratic Republic) and the Spanish cities Ceuta and Melilla. As of 2018, the region had a population of over 100 million people.

Through the 18th and 19th centuries, English sources often referred to the region as the Barbary Coast or the Barbary States, a term derived from the demonym of the Berbers. Sometimes, the region is referred to as the Land of the Atlas, referring to its Atlas Mountains.

The Maghreb is usually defined as encompassing much of the northern part of Africa, including a large portion of the Sahara Desert, but excluding Egypt and Sudan, which are considered to be located in the Mashriq — the eastern part of the Arab world. The traditional definition of the Maghreb — which restricted its scope to the Atlas Mountains and the coastal plains of Morocco, Algeria, Tunisia and Libya — was expanded in modern times to include Mauritania and the disputed territory of Western Sahara. During the era of Al-Andalus on the Iberian Peninsula (711–1492), the Maghreb's inhabitants — the Muslim Berbers, or Maghrebi — were known by Europeans as the "Moors".

Before the establishment of modern nation states in the region during the 20th century, the Maghreb most commonly referred to a smaller area, between the Mediterranean Sea and the Atlas Mountains in the south. It often also included the territory of eastern Libya, but not modern Mauritania. As recently as the late 19th century, the term "Maghreb" was used to refer to the western Mediterranean region of coastal North Africa in general, and to Algeria, Morocco, and Tunisia in particular.

During the rule of the Berber kingdom of Numidia, the region was somewhat unified as an independent political entity. This period was followed by one of the Roman Empire's rule or influence. The Germanic Vandals invaded after that, followed by the equally brief re-establishment of a weak Roman rule by the Byzantine Empire. The Islamic caliphates came to power under the Umayyad Caliphate, the Abbasid Caliphate and the Fatimid Caliphate. The most enduring rule was that of the local Berber empires of the Ifranid dynasty, Almoravid dynasty, Almohad Caliphate, Hammadid dynasty, Zirid dynasty, Marinid dynasty, Zayyanid dynasty, Hafsid dynasty and Wattasid dynasty, extending from the 8th to 13th centuries. The Ottoman Empire also controlled parts of the region for a period.

In the 19th and early 20th centuries, the region was ruled by European powers: France (Algeria, Tunisia, Mauritania and most of Morocco), Spain (northern Morocco and Western Sahara), and Italy (Libya). Italy was expelled from North Africa by the Allies in World War II. Decolonization of the region continued in the decades thereafter, with violent conflicts such as the Algerian War, the Ifni War and the Western Sahara War.

Algeria, Libya, Mauritania, Morocco, and Tunisia established the Arab Maghreb Union in 1989 to promote cooperation and economic integration in a common market. The union implicitly included Western Sahara under Morocco's membership. However, this progress was short-lived, and the union is now largely dormant. Tensions between Algeria and Morocco over Western Sahara re-emerged, reinforced by the unresolved border dispute between the two countries. These two conflicts have hindered progress on the union's joint goals.