La Siguanaba

La Siguanaba (Hideous Woman in Nahuatl language), is a legendary figure from El Salvador mythology. She was once named Sihuehuet (Beautiful Woman), who had an affair with the son of the god Tlaloc, and gave birth to her son Cipitio. She was never a good mother, and would constantly neglect her son. For this, Tlaloc cursed her, and granted Cipitio eternal youth. Now, La Siguanaba haunts the rivers, where she lures unfaithful men in with her beauty, just to reveal her monstrous true form.

Illustrated in Procreate.