Simbi is a family of serpent lwa of Haitian Vodou who dwell in springs, rivers, pools and the crossroads of fresh water, aloof, secretive spirits, patrons of magic and of the knowledge that passes between the worlds. Where many of the great lwa descend from the Fon and Yoruba traditions of the Bight of Benin, the Simbi carry a clearly Kongo inheritance: among the Bakongo peoples of Central Africa the bisimbi (singular simbi) are water-and-nature spirits that inhabit clear deep springs and still pools and may show themselves as a serpent, and this Central African stream, carried by enslaved people to the Caribbean, remains legible in the Haitian Simbi. They are the guardians of the sources of water, on which life depends, and messengers who carry communication between human beings and the other spirits; they are associated with rain, with the green places where water rises, and with the working of charms and secret knowledge, so that they are approached with care and are said to be easily offended and quick to withdraw.
Some are counted among the Rada spirits and some among the fiercer Petwo, reflecting the several forms the family takes. In the correspondences with the Catholic saints the Simbi are variously associated, often with the Magi or with saints connected to water. Vodou is a living religion, and the Simbi are among its more mysterious powers, the serpent-spirits of the spring and the river, keepers of the fresh water and of the secrets that move between the worlds.