Your ancestor lost his mind, obsessed. He and his shipmen slaughtered these beautiful creatures in cold blood. Genocide — That's your legacy.
Helen Hawkins to Ben Pownall

Merfolk (or specifically mermaids and mermen) are mythological sea creatures with the upper body of a human and the lower body of a scaly fishtail.


Bristol Cove was once home to mermaids. Over a hundred years ago, a Siren enchanted the men of Bristol Cove and a Captain, Charles H. Pownall, heard her Siren Song. She emerged from the sea to greet him and he fell in love with her. The Siren and Charles H. Pownall had a daughter that was born in transition and appeared deformed. He took his daughter to the Haida, people who weren't afraid and had them cure her of her deformity. The Siren left, going back to her home in the sea, believed that her daughter was killed, and never returned. The Captain was so bitter and heartbroken that he and his men sought vengeance on the mermaids and slaughtered them.

Ryn and Donna were racing in the sea one night when Donna was captured by one of the fishermen and brought aboard the ship. She attacked Chris and began to sing her siren song. The military then arrived in helicopters and took her to their military base, where she was placed in a tank and experimented on. Scientists took a sample of her DNA and placed it into a fully paralyzed rat which caused it to be cured and healed.

Donna escaped the military facility and Ryn and Donna finally returned home to the colony.

Levi and Donna attacked Ben and the other fisherman board the ship. They got hurt but escaped.

Donna, Katrina, and Levi came onshore to Bristol Cove. Donna wanted to bring Ryn back to the colony with them, and Katrina and Levi wanted to kill Ryn. Katrina and Ryn fought and Ryn usurped her position as Alpha leader of the colony.


Merfolk have a human-like upper body and the lower body of a scaly fish's tail instead of legs. While mermaids have the upper body of a beautiful female human with flowing long hair that covers their backs, mermen have the upper body of a handsome, muscular human male. Merfolk have blue eyes which comes in varying shades. Both mermaids and mermen have dagger-like teeth and talons used for catching and tearing prey. They also have gill slits on their rib cage that enables them to breathe underwater and syndactyly, digits fused together forming webbed hands, which reduce water resistance when they swim. Their scaly fishtails are silvery gray and has pelvic fins on either side of their tail, which assist them as they move vertically or turn sharply in the water. A large dorsal fin runs down their backs while a much smaller one runs down the backs of their tails. In addition, they have a vertical tail fluke, similar to a cetacean's, used for propulsion. A barbed stinger at the end of their tail that is very sharp and piercing and is used as a weapon or for self-defense. Some Merfolk such as Levi and Katrina do not appear to have barbs on their tails. They both have grey skin that is covered with silvery-grey scales of varying hues, including the human half. Their voice boxes are a hybrid of a larynx and a syrinx at the base of their trachea. Mermen are seen with spikes on their backs.

Merfolk can spend more time on the surface the more they transform to occupy land. It is currently unknown how Merfolk reproduce. Although it has been shown that Merfolk can reproduce with humans as the Siren had a daughter with Charles H. Pownall. Mermaids possess a strange, alluring quality that many humans are drawn to which is present in both their human and aquatic forms. Warrior mermen are typically seen carrying spears they use as weapons to attack and kill their enemies.


Season 1

Season 2

  • TBA

About Merfolk

In their natural state in the water, they see you as prey. Their instinct is to kill.
— Helen to Ben about the purpose of the merfolk
They're highly intelligent. More so than humans.
— Helen to Maddie

Merfolk usually only kill for survival. According to Helen Hawkins, Merfolk are highly intelligent creatures, more so than humans at least. This is displayed in Ryn's extremely quick grasp of the English language and her memory also appears to be quite superb. Merfolk have some difficulty adjusting to life on land; though given their inexposure to human culture, this can be expected. Because Merfolk have some difficulty speaking human languages, they tend not to speak much.


Merfolk live in groups of colonies in various parts of the sea. These colonies are led by matriarchal leaders, according to Helen. The leader of a colony is known as the Alpha leader. Katrina is the former Alpha leader of a colony; Ryn later replaced her as Alpha after defeating her in combat.

Known Merfolk


  • Ryn (Siren, current Alpha leader)
  • Donna (Siren)
  • Katrina (former Alpha leader)
  • Ryn and Donna's Mother †
  • Unnamed Siren †
  • Unnamed three mermaids


  • Levi (warrior)
  • Unnamed merman

Merfolk/Human Hybrids

  • Helen Hawkins (1/8 mermaid)
  • Helen's Grandmother(Charles Pownall and his mermaid's daughter) (1/2 mermaid) †

Powers and Abilities

  • Amphibious Transformation: Merfolk are able to take on an ordinary human appearance through a painful metamorphosis to blend in with modern society and avoid being detected for varying lengths of time. Merfolk who gained legs and later went back into the water go through a painful transformation process. Their teeth become dagger-like and their skin turns into silvery-gray scales. Their hands become talons and a dorsal fin emerges from their backs. Their legs fuse together to form a scaly fishtail. Merfolk can only transform in ocean water, proven when Ryn was pushed into a swimming pool but remained in her human-like state. When they transform into their human-like forms, they shed their scaly fishtails.
  • Aquatic Habitation: Merfolk can survive and adapt to underwater environments including enduring high water pressure and extreme water temperatures. They are able to survive the high water pressure of the deep ocean and can swim in colder waters.
  • Speed Swimming: Merfolk are able to swim at extremely high rates of speed with minimal restrictions to water resistance.
  • Extraordinary Strength: Merfolk are noticeably physically much stronger than humans. Ryn was able to overpower a large adult male and threw a pipe with enough force for it to pierce a wall. She was also able to lift an anchor and throw it without difficulty. 
  • Siren Song: Sirens are exclusively able to emit a captivating, ethereal, and irresistible hypnotic singing voice that lures anyone who hears it toward the mermaid. Apparently those who are exposed to it have lingering side effects; the exact nature of these symptoms are as of yet not clearly defined. Ben compares it to a drug, describing it as something he needs. Eventually, the Siren Song leads the man that hears it to hallucinate seeing that mermaid everywhere and hearing their Siren Song out in the ocean. The victim will then be driven into the water to find that mermaid and eventually drown. Whether or not both genders of Merfolk possess this ability is not yet known.
  • Enhanced Regeneration: Merfolk possess greater regenerative capabilities than humans. They heal quickly from non-fatal injuries within a short period.


  • Dehydration: Merfolk are unable to survive on land for extended periods of time. After prolonged deprivation of water, they will begin to asphyxiate, and their skin will become extremely dry and irritated. After an extensive period of dehydration, their body will begin to shut down. Merfolk are able to spend more time on the surface each time they transform to occupy land.
  • Mortality: Since Merfolk are living creatures, they can be killed by conventional means (e.g. blood loss, decapitation, starvation, suffocation, and etc.).


Their diet consists of seafood such as fish, shrimp, clams, crab, and lobsters. In Pilot, a shark's head was seen with bite marks indicting Merfolk eat shark as well. Ryn also killed and ate a rat when she was first on land.


When Merfolk die, their family takes their body and swims for a long time to the deep ocean so no other animal can find it and leave it in a special place, like a funeral.


  • Merfolk seem to not have birth given names.
  • The hybrid child of a Merfolk and a human will be born in transition and appear deformed.
  • It is unknown if hybrid children of Merfolk and humans have the same powers, abilities, and weaknesses Merfolk do.
  • It is currently unknown how long an average mermaid and merman can live, although it has been confirmed by Helen that once a hybrid has completed its transition, it can live for a very long time.
  • In "Aftermath," when Ryn went into the water to save Ben from drowning, she did not resort to her natural instinct to kill, unlike when she first transformed into her mermaid form in "Pilot. This could be because of her mutual trust in Ben and Maddie building up over time.
  • It is currently unknown how Merfolk reproduce.
    • It has been shown that Merfolk can reproduce with humans as the Siren had a daughter with Charles H. Pownall.
  • It is currently unknown as to which of Helen's parents was 1/4th mermaid and passed down the mermaid heritage to her.