In the cultures of the Horn of Africa and adjacent regions of the Middle East, Zār (Arabic: زار, Ge'ez: ዛር) is the term for a spirit assumed to possess individuals, mostly women, and to cause discomfort or illness. The so-called zār ritual or zār cult is the practice of reconciling the possessing spirit and the possessed individual. Zār possession is often considered lifelong and the rituals associated with it are a form of adorcism, though some have falsely attributed it as an exorcism rite because it involves possession. It is similar to the Maghreb's Hamadsha, Hausa Animism, and various African Traditional religions, such as Voodou.

Zār is also a form of predominantly (not solely) women's entertainment that has become popular in the contemporary urban culture of Cairo and other major cities of the Islamic world. Participants have compared it to how those not involved in zār go to the discotheque. Zār gatherings involve food and musical performances and they culminate in ecstatic dancing, lasting between three and seven nights.

The tanbūra, a six-string bowl lyre, is often used in the gathering. Other instruments include the manjur, a leather belt sewn with many goat hooves, and various percussion instruments.

The term zār may be used to mean various different things in the places the belief is found: it may refer to the hierarchy of zār spirits, an individual spirit of this type, the ceremonies concerning these spirits, the possessed person, or the troubles caused by these spirits.

Scholarship in the early 20th century attributed Horn of African origin to the custom, although there were also proposals suggesting Persian or other origins. Thus, Frobenius suggested that zār and bori, a comparable cult in Hausa culture, were ultimately derived from a Persian source. Modarressi (1986) suggests a Persian etymology for the term. The first known instance of the word zār used in Ethiopia to refer to a possessing spirit is from a 16th-century Ge'ez manuscript. However, it is unknown if zār rituals were being practiced in 16th century Ethiopia (Abyssinia), and if so, what form they took. The first record of zār ceremonies is from the 1800s in Ethiopia, however by this time the ceremonies were already elaborate and being practiced in a large area, indicating these ceremonies had been practiced for sone time before recording.

Some also strongly feel the practice originated in West Africa among native religious curing practices there.

The origin of the word is unclear; Walker (1935) suggested the name of the city of Zara in northern Iran, or alternatively the Arabic root z-w-r "to visit" (for the possessing spirit "visiting" the victim). The Encyclopedia of Islam of 1934 favoured an Ethiopian origin of the word. Hager El Hadidi suggested a possible Hebrew origin from zwr (in Hebrew meaning to "turn aside, deviate, go away") or zr ("one who distances or removes himself"), owed to Jewish craftsmen in the Red Sea area. Another theory is that it derives from the name of the supreme deity of the pagan Kushites.

The practice allegedly originated in Harar, Ethiopia via Sheikh Abadir, and was introduced by Harari and Somali women to Aden in Yemen.