A soucouyant, among other names, is a kind of shape-shifting, blood-sucking hag present in Caribbean folklore.
Names
The spirit has several regional names:
Ol' Higue or Ole Haig in Guyana, Belize and Jamaica
Asema in Suriname
Hag in The Bahamas and Barbados
Soucouyant or soucriant in Louisiana and elsewhere in the Caribbean
Legend
The soucouyant is a folklore character who appears as a reclusive old woman by day. By night, she strips off her wrinkled skin and puts it in a mortar. In form of a fireball, she flies across the dark sky in search of a victim. The soucouyant can enter the home of her victim through any sized hole such as cracks and keyholes.
Soucouyants suck humans' blood from their arms, necks, legs and other soft regions while they sleep, leaving black and blue marks on the body in the morning. If the soucouyant draws too much blood, it is believed that the victim will either die and become a soucouyant or perish entirely, leaving her killer to assume her skin. The soucouyant practices black magic. Soucouyants trade their victims' blood for evil powers with Bazil, the demon who resides in the silk cotton tree.
To expose a soucouyant, it is believed one should heap rice around their house or at the village crossroads; the creature will be obligated to gather the rice, grain by grain, and be caught in the act. To destroy her, coarse salt must be placed in the mortar with her skin so that she perishes, unable to put it back on. The skin of the soucouyant is considered valuable and is part of black magic rituals.
Belief in soucouyants is still preserved to an extent in Guyana, Suriname and some Caribbean islands, including Dominica, Haiti and Trinidad. Many Caribbean islands have plays about the soucouyant and many other folklore characters. Some of these include Trinidad, Grenada and Barbados.
Origin
Soucouyants belong to a class of spirits called jumbies. Some believe that soucouyants were brought to the Caribbean from European countries in the form of French vampire-myths. These beliefs intermingled with those of enslaved Africans.
In the French West Indies, specifically the islands of Guadeloupe and Martinique, and also in Suriname, the Soukougnan or Soukounian is a person able to shed his or her skin to turn into a vampiric fireball. In general, these figures can be of any gender and age.
The term "Loogaroo" also used to describe the soucouyant, possibly comes from the French word for werewolf: Loup-garou; often confused with each other since they are pronounced the same. In Haiti, what would be considered a werewolf, is called jé-rouges ("red eyes"). As in Haiti, the Loogaroo is also common in Mauritian culture.
With the passage of time and gradual changes in the story, the soucouyant is no longer exclusively described as an elderly woman.
Yoruba Origins
In The Bahamas there is a similar thing known as the Hag. The Hag, which is the same as the Soucouyant but with a different name, is very similar to the traditional definition of the Yoruba witch, known as Aje. Many Bahamians who descended from the Yoruba referred to old Congolese women as witches who shed their skins in the night and sucked your blood. This have many parallels to the Yoruba Aje with a few differences. Among the Yoruba, the Aje left her body and turned into an animal, but the Hag sheds her skin and turns into a ball of fire. Both the Hag and the Aje are associated with old women, leaving their bodies behind and sucking blood. It is likely the origin of the Hag and the Soucouyant have a strong connection to the Aje, or the witch of the Yoruba people.
For more about the Bahamian Hag, read "Items of Folk-lore from Bahama Negroes by Clavel published in 1904. The parallels of the Bahamian Hag and Yoruba was made during the 19th century by Alfred Burdon Ellis in his book about the Yoruba published in 1894. But he associated it with the Yoruba spirit of nightmare, known as Shigidi.
For more about the Yoruba Aje, read Divining the self by Velma E Love, who describes the Aje as: "a blood-sucking, wicked, dreadful cannibal who transforms herself into a bird at night and flies to distant places, to hold nocturnal meetings with her fellow witches."