Sihuanaba
The Cegua, La Sihuehuet or Siguanaba, Cigua or Siguanaba is a supernatural character from Central American folklore, though it can also be heard in Mexico. It is a shapeshifting 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.
Source: Wikipedia
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