Haitian Vodou is an African diasporic religion that developed in Haiti between the 16th and 19th centuries. It arose through a process of syncretism between several traditional religions of West and Central Africa and Roman Catholicism. There is no central authority in control of the religion and much diversity exists among practitioners, who are known as Vodouists, Vodouisants, or Serviteurs.

Vodou revolves around spirits known as lwa. Typically deriving their names and attributes from traditional West and Central African divinities, they are equated with Roman Catholic saints. The lwa divide up into different groups, the nanchon ("nations"), most notably the Rada and the Petwo. Various myths and stories are told about these lwa, which are regarded as subservient to a transcendent creator deity, Bondye. This theology has been labelled both monotheistic and polytheistic. An initiatory tradition, Vodouists usually meet to venerate the lwa in an ounfò (temple), run by an oungan (priest) or manbo (priestess). A central ritual involves practitioners drumming, singing, and dancing to encourage a lwa to possess one of their members and thus communicate with them. Offerings to the lwa include fruit, liquor, and sacrificed animals. Offerings are also given to the spirits of the dead. Several forms of divination are utilized to decipher messages from the lwa. Healing rituals and the preparation of herbal remedies and talismans also play a prominent role.

Vodou developed among Afro-Haitian communities amid the Atlantic slave trade of the 16th to 19th centuries. Its structure arose from the blending of the traditional religions of those enslaved West and Central Africans, among them Yoruba, Fon, and Kongo, who had been brought to the island of Hispaniola. There, it absorbed influences from the culture of the French colonialists who controlled the colony of Saint-Domingue, most notably Roman Catholicism but also Freemasonry. Many Vodouists were involved in the Haitian Revolution of 1791 to 1801 which overthrew the French colonial government, abolished slavery, and transformed Saint-Domingue into the republic of Haiti. The Roman Catholic Church left for several decades following the Revolution, allowing Vodou to become Haiti's dominant religion. In the 20th century, growing emigration spread Vodou abroad. The late 20th century saw growing links between Vodou and related traditions in West Africa and the Americas, such as Cuban Santería and Brazilian Candomblé, while some practitioners influenced by the Négritude movement have sought to remove Roman Catholic influences.

Most Haitians practice both Vodou and Roman Catholicism, seeing no contradiction in pursuing the two different systems simultaneously. Smaller Vodouist communities exist elsewhere, especially among the Haitian diaspora in the United States. Both in Haiti and abroad Vodou has spread beyond its Afro-Haitian origins and is practiced by individuals of various ethnicities. Vodou has faced much criticism through its history, having repeatedly been described as one of the world's most misunderstood religions.