Merpeople are a sentient species of underwater-dwelling Beings found worldwide. They possess their own sophisticated culture, language, and social structures, existing largely independently of the wizarding world. Though capable of breathing air for short periods, they are entirely adapted to an aquatic life. The Ministry of Magic classifies them as Beings of near-human intelligence and they are self-governing. They are known for being reclusive and generally suspicious of land-dwellers, though they have been known to form alliances with wizards in times of great need. The oldest recorded merpeople are known as Sirens (Greece), while those in Scotland are known as Selkies and in Ireland as Merrows (Fantastic Beasts and Where to Find Them).
The merpeople of the Great Lake at Hogwarts School of Witchcraft and Wizardry, the primary group seen in the novels, have a distinct and rather intimidating appearance. They possess greyish skin, long, wild, dark green hair, and piercing yellow eyes with yellowed, broken teeth. From the waist down, they have a large, silver, muscular fish-tail. This appearance starkly contrasts with the traditionally beautiful depictions of mermaids in Muggle folklore. Their physiology is perfectly suited for their aquatic environment. They are powerful swimmers and can exist at the cold, dark depths of the Great Lake. While they can survive above water, their voices, which are melodious and understandable underwater, become harsh, unpleasant screeches in the open air. Their intelligence is comparable to that of wizards, allowing for complex communication and societal organization.
Merpeople live in organized communities, often constructing villages from crude stone. The colony in the Great Lake has a settlement featuring dwellings adorned with carvings of krakens and other sea creatures, and some homes have cultivated gardens of gillyweed. They are known to domesticate creatures like the Grindylow. Their society is structured with a clear hierarchy, led by a chief. During the 1994-1995 school year, the chieftain of the Great Lake colony was Murcus. They are skilled artisans and warriors, creating their own art (as seen in a painting in Albus Dumbledore's office) and fashioning formidable spears for hunting and defense. The primary language of the merpeople is Mermish, a language described as sounding like screeching when heard above the surface. A few wizards, most notably Albus Dumbledore, have mastered Mermish, allowing for direct diplomacy.
The relationship between merpeople and wizards is complex. The Ministry of Magic's official “Being” classification grants them rights and protection, recognizing their intelligence and right to self-governance. Historically, they have been wary of land-dwellers and have avoided integration into the wizarding political system. However, individuals like Albus Dumbledore fostered positive relations, communicating with the merpeople chieftainess and securing their cooperation for the Triwizard Tournament. Their decision to fight in the Battle of Hogwarts represents a pivotal moment, suggesting a deep-seated loyalty to Hogwarts and an understanding of the existential threat posed by Lord Voldemort.
The term “merpeople” is a compound of “mer,” derived from the Old French mer and the Latin mare, meaning “sea,” and “people.” The term follows the pattern of “mermaid,” which comes from the Old English mere (sea, lake) and “maid.” “Merpeople” serves as a more inclusive, gender-neutral term for the species.