This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Yacuruna (Amazon)
The Yacuruna are a mythical water people of the Amazon basin who live in beautiful underwater cities, often at the mouths of rivers. Belief in the Yacuruna is most prominently found among indigenous people of the Amazon. The Yacuruna is described as being hairy with a backward-facing head and deformed feet.
Illustrations depict the Yacuruna as a man-like creature accompanied by a serpent and riding a crocodile. The Yacuruna roam the Amazon rainforest at night using black crocodiles as canoes. During the day they sleep at the bottoms of rivers and lakes with one eye open. They have the ability to communicate with aquatic animals of the Amazon and have ultimate control over them.