Obeah, also spelled Obiya or Obia, is a broad term for African diasporic religious, spell-casting, and healing traditions found primarily in the former British colonies of the Caribbean. These practices derive much from West African traditions but also incorporate elements of European and South Asian origin. Many of those who practice these traditions avoid the term Obeah due to the word's pejorative connotations in many Caribbean societies.

Central to Obeah are ritual specialists who offer a range of services to paying clients. These specialists have sometimes been termed Obeahmen and Obeahwomen, although often refer to themselves in other ways, for instance calling themselves "scientists", "doctors", or "professors". Important in these ritual systems is engagement with the spirits and the manipulation of supernatural forces. A prominent role is played by healing practices, often incorporating herbal and animal ingredients. Other services include attempts to achieve justice for a client or to provide them with spiritual protection. Cursing practices have also featured in Obeah, involving the making of objects to cause harm or the production of poisons. There is considerable regional and individual variation in the nature of the rituals that practitioners of Obeah have engaged in.

Amid the Atlantic slave trade of the 16th to 19th centuries, thousands of West Africans, many Ashanti were transported to Caribbean colonies controlled by the British Empire. Here, traditional African religious practices assumed new forms, for instance being employed for the protection of Maroon communities. Enslaved Africans also absorbed British influences, especially from Christianity, and later from the Hinduism and Islam introduced by indentured South Asian migrants. The colonial elites disapproved of African traditions and introduced laws to prohibit them, using the term Obeah as a general label for these practices from the 1760s on. This suppression meant that Obeah emerged as a system of practical rituals rather than as a broader communal religion akin to Haitian Vodou or Cuban Santería. After the British abolition of slavery in the 1830s, new laws were introduced against Obeah, increasingly portraying it as fraud, laws that remained following the end of imperial rule. Since the 1980s, Obeah's practitioners have campaigned to remove these legal restrictions, often under the aegis of religious freedom.

The term Obeah has been used for practices in the Caribbean nations of the Bahamas, Barbados, Belize, Grenada, Guyana, Jamaica, Saint Lucia, Saint Vincent and the Grenadines, Suriname, Trinidad and Tobago, and the Virgin Islands. Caribbean migrants have also taken these practices elsewhere, to countries like the United States, Canada, and United Kingdom. In many Caribbean countries Obeah remains technically illegal and widely denigrated, especially given the negative assessment towards it evident in religions like Evangelical Protestantism and Rastafari.

Obeah incorporates both spell-casting and healing practices, largely of African origin, although with European and South Asian influences as well. It is found primarily in the former British colonies of the Caribbean, namely Suriname, Jamaica, the Virgin Islands, Trinidad, Tobago, Guyana, Belize, the Bahamas, St Vincent and the Grenadines, and Barbados. Aside from the common use of Obeah, other spellings that have been used include Obiya, Obey, Obi, and Obia, the latter common in Suriname and French Guiana.

The term Obeah encompasses a varied range of traditions that are highly heterogenous and display much regional variation. The Hispanic studies scholars Margarite Fernández Olmos and Lizabeth Paravisini-Gebert defined Obeah as "a set of hybrid or creolized beliefs dependent on ritual invocation, fetishes, and charms", while the historian Diana Paton termed it "a very wide range of practices that, broadly speaking, invoke the ritual manipulation of spiritual power". For the historians Jerome Handler and Kenneth Bilby it was "a loosely defined complex involving supernatural practices largely related to healing and protection". The historian Thomas Waters called Obeah a "supernatural tradition", and described how it "blended West African rituals with herbalism, Islam, Christianity and even a smattering of British folk magic". The term was originally used by Europeans, according to Handler and Bilby, as "a catch-all term for a range of supernatural-related ideas and behaviours that were not of European origin and which they heavily criticized and condemned."

Throughout history, the term Obeah has rarely been used as a self-description of a person's own practices. In the Caribbean, practitioners of folk healing traditions are often reluctant to publicly describe what they do as Obeah; there are some people who will privately describe what they do as Obeah, but used other words publicly. Historically, those who were accused of practicing Obeah in criminal court rarely used that term itself. Some practitioners instead refer to it as "Science", or as working, doing a job, doing some good, practicing, clearing. In Jamaica, another term for Obeah is "iniquity," probably deriving from the repeated Protestant admonitions that Obeah was an iniquitous practice.

Paton noted that, in encompassing a broad range of supernaturally-oriented practices, the term Obeah served a "roughly equivalent" role in the Anglophone Caribbean to the terms conjure and root work (or Hoodoo) in the United States and the Quimbois [fr; ht] of Francophone Caribbean islands Guadeloupe and Martinique. Fernández Olmos and Paravisini-Gebert suggested that Quimbois was essentially "a variation of Obeah". Obeah has both similarities and differences with other Afro-Caribbean religious traditions such as Haitian Vodou or Cuban Santería and Palo. Unlike them, it lacks communal rituals or a system of liturgy, and in contrast to the followers of these traditions, there is little evidence that Obeah's practitioners have regarded it as "their religion". Fernández Olmos and Paravisini-Gebert took the view that Obeah was not a religion per se, but is a term applied to "any African-derived practice with religious elements". Obeah exists at the borders of what both Christians and social scientists have typically recognised as "religion," and as such it has historically often been classified not as religion but as "magic," "witchcraft," "superstition," or "charlatanism."