"El Trauco" is a legendary monster said to inhabit the archipelago of Chiloé, in the South of Chile. Like most legendary monsters, the information on El Trauco is scattered and contradictory. I first learned about El Trauco when I visited Chiloé, a visit that led to me becoming suddenly and very ill. Afterwards, when I mentioned that it felt almost like a curse was placed upon me, someone said "Oh, like El Trauco".
Chiloé is an island about the size of Delaware in the south of Chile, close to Patagonia, that is famous for its constant rain, as well as being the origin of most of the culinary potato stock used in the world. Even today, there are no bridges to the island, and it has always been a somewhat secluded place. Thus, the presence of the elusive Trauco is keeping with the spirit of the island.
El Trauco is described as a short, ugly and evil man who is nevertheless hypnotically sexually attractive to all women. A woman who comes near El Trauco is irresistibly drawn towards him, with the couplings usually or always ending in pregnancies. What happens to men that come near El Trauco is less clear, although sometimes they may be injured or cursed. Most commentaries I've read and people I've talked to have told me that the purpose of the legend of El Trauco was to explain away premarital or extramarital pregnancy in a traditionalist society, because a woman who became pregnant outside of marriage could always just claim the intervention of the hypnotically irresistible El Trauco. But the legend is so buried in hundreds of years of folklore that its original meaning, and what degree of nefariousness it should be analyzed with, have been lost to history.
Just be careful if you go to Chiloé