Wikipedia
Sihuanaba
The Sihuanaba, La Siguanaba, Cigua or Cegua is a supernatural character from Central American folklore. It is a shape-changing spirit that typically takes the form of an attractive, long haired woman seen from behind. She lures men away into danger before revealing her face to be that of a horse or, alternatively, a skull.
The Siguanaba and its variants may have been brought to Latin America from Spain during the Colonial Period, used by the colonists as a means of exercising control over the indigenous and mestizo population.