Merfolk, Mercreatures, Mermen or Merpeople are legendary water-dwelling, human-like beings. They are attested in folklore and mythology throughout the ages in various parts of the world. Merfolk, Merpeople, or simply Mer refers to humanoid creatures that live in deep waters like Mermaids, Sirens, Cecaelia etc.
In English, female merfolk are called mermaids, although in a strict sense, mermaids are confined to beings who are half-woman and half-fish in appearance; male merfolk are called mermen. Depending on the story, they can be described as either ugly or beautiful.
Chinese rényú (人魚) stands for "merfolk", but in ancient geographical or natural historical tracts, the term referred to "human-fish" or "man-fish" purported to inhabit rivers or lakes in certain parts of China. The Japanese analogue ningyo (人魚) likewise translates to "merfolk" while, at the same time, having also applied to various human-like fish recorded in writings from medieval times into the Edo Period.