This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Fuath (Celtic)
A fuath is a class of malevolent spirits in Scottish Highland folklore, especially water spirits. In Sutherland was the so-called Moulin na Vaugha/Fouadh, ‘Mill of the Fuath', haunted by the fuath and her son, the amorphous brollachan. The mill was along a stream off Loch Migdale, and belonged to the Dempster family (Skibo Castle) estate.
A fuath once seen at this mill was a nose-less banshee with yellow hair wearing a green silk dress; in the story of its capture[a] it was tormented into submission by use of steel (awl, and more effectively by a sewing needle), but it turned to a jellyfish-like mass when light was shone on it. A fuath on the estate farm, encountered on a different occasion, had webbed feet. They sometimes reputedly intermarry with human beings (typically the female), whose offspring have developed a mane and tail.