Merpeople are sentient beings who live under the water. They can breathe air for short periods of time. Merpeople are intelligent folk who have developed their own culture and social structures. Merpeople are found all over the world.

The merpeople have grayish skin and long, wild, dark green hair. Their eyes are yellow, as are their broken teeth, and they wear thick ropes of pebbles around their necks. Their powerful, silver fish tails allow them to swim expertly, while the upper parts of their bodies resemble humans. Merpeople are very tall. Harry encountered one in the lake near Hogwarts who was seven feet tall with a long green beard and a choker of shark fangs, carrying a spear. The voices of merpeople sound like screeching above water but are understandable beneath the waves, where they sound croaky. Their own language is called Mermish.

The Merpeople's village in the Lake

• located in the center of the lake, a quarter of a mile from Hogwarts castle (GF26)
• the leader of the village is Merchiefteness Murcus
• The edge of the village is marked by a large rock with paintings of merpeople on it; they are carrying spears and chasing the giant squid.
• The village consists of clusters of crude stone dwellings stained with algae
• some houses have gardens of weed around some of them
• a few merpeople keep a pet grindylow tied to a stake outside their door. 
• in the center of the village, the houses line a village square in which rises a crude sort of statue of a gigantic merperson hewn from a boulder