A Morgan (a Breton class of water-fairy), a variant of Ahes and the name by which she is known as the daughter of Gradlon, who threw her into the sea after she had caused the sea to engulf Ys, a domain she is still said to inhabit, luring sailors to their death in the drowned city.

It is thought by some that her class of fairy, also known as Mari-Morgans, was the origin of Morgan Le Fay.