Merfolk

Mermaids are water-based creatures traditionally imagined as having a top half indistinguisable from humans and a fish-like lower half, usually in the form of one tail with caudal fin at the end. There are many variations, though, which are largely of recent nature, and there is an amount of overlap with other aquatic creatures, such as water monsters and sirens. Mermaids are predominantly thought of as female and male ones tend to be given the designation of "mermen", or the creatures are degendered with terms like "merfolk" or "merperson". The nature attributed to mermaids ranges from murderous, for either entertainment or food, to saviorhood of children and sailors.

Etymology
The modern word "mermaid" has its roots in the first half of the 14th century as "mermayde", prior to which the creature was known as a merewif or meremenn. The recurring "mer" portion means "sea" or more generally "large body of water", and words like it can be found in many European countries. The suggested Proto-Indo-European word is therefore "móri".

Mermaids are regularly conflated with sirens, such that some European languages do not differentiate between the two and call both a variation of "siren". Modern day Greek does differentiate, using "σειρήνα" ("seirína") for sirens and "γοργόνα" ("gorgóna") for mermaids. Meanwhile, "γοργόνα" is the word used both for mermaids and gorgons.

Stories featuring seafolk have started playing with mermaid variations as to the shape and qualities of the tail since the second half of the 20th century. Of these, the only one with a name of its own are the octopus-based seafolk, which are named "cecaelias" or "cilophytes". These names originate from a story featuring such a creature named "Cilia" in issue #16 of the Vampirella comic magazine, released in March of 1972. The creature is named Cilia and introduces herself as a cilophyte. "Cecealia" is presumed to be a corruption of "Cilia". Arguably this makes it a "meaningless" word, but "cilia" itself seems to be a name picked in reference to microscopic hairlike structures within or on mobile lifeforms. It is unclear what "cilophyte" is supposed to mean. "-Phyte" comes from Ancient Greek "φύειν" ("phuein", "to grow"/"to generate") through "φυτόν" ("phuton", "plant"/"growth"/"descendent") and probably means "growth" in context. The "cilo-" bit is a mystery, though it is possible to be a typo for "cilio-", which is the same word as "cilia". Another theory is that it's an adaption of "Scylla". The Scylla is an Ancient Greek monster who's sometimes depicted as having multiple tails. The two-tailed mermaid, for instance, is based on Etruscan images of her, and Cilia's tentacles are divided in two tails too. As such, it's possible the author aimed for a name essentially meaning "growth like Scylla's".

History
Before the history of mermaids can be explored, it is well to understand that there are two meanings to the word, one indicating a creature — with or without fish tail — and the other a shape. Mermaids as half fish and half human creatures are part of a global network of predominantly female water entities, such as morgens, nixies, sirens, selkies, kelpies, ceasgs, rusalkas, xanas, and a huge collection of water spirits in Ancient Greek mythology among which the naiads — and that's keeping it to European variants only. Most of them are generally imagined as indistinguishable from a human, or at least when they interact with them. As such, artists sometimes take conscious liberties to emphasize the water aspect by giving these creatures fish parts. Even sirens, who are defined by bird parts, have been regularly given fish parts instead for well over a millennium now. Possibly coincidence but equally as intriguing, fish~bird fluidity occurred earlier with the Apkallu too. Whether the half-fish shape makes water spirits that aren't mermaids in those instances mermaids is a matter of perspective. To complicate the situation, there's also some overlap between mermaids and snake-human hybrid creatures: lamias and nāgas, who have a snake-like lower body, as well as gorgons, who have snake hair. The overlap is best seen in the figures of Melusine, who depending on the version of the story is either a lamia or a mermaid, and Euryale, whose name could mean both "wide-stepping" and "she of the wide briny sea".

European mermaids and European-inspired mermaids trace their origin through a complex network of events to the Mediterranean Basin and the Middle East and, in short, have in the spotlight Enki, also known as Ea, a Fish God, Dagon, also a Fish God, the aforementioned Apkallu, seven sages that brought civilization to humanity, and Adapa or Uanna, the first of the Apkallu and first creation of Enki. As far as written evidence goes, Enki goes back at least to the third millennium BCE, showing up in legal codes created by Urukagina, a 24th century BCE king of Lagash, which is located in what now is Iraq, and in the 2500-2250 BCE Ebla tablets found in Ebla, which is situated in modern-day Syria. Enki is a god of all forms and functions of water, fertility, civilization, and the creation of humankind is attributed to him in several myths, though often in cooperation with his mother Nammu. His symbols include reeds, the turtle, the goat, and fishes, and the latter two were fused during his worship into the capricorn that would later be adopted into the mythology of Ancient Greece. Dagon is similar to Enki, being a fertility god associated with fish and grain, and also originates in the third millennium BCE. Early written material on this god have been found in Mari, these days located in Syria, and have been dated to about the 24th century BCE.

Stele with the relief of a half-human, half-fish hybrid presumably representing Oannes or a related mythical creature. Staatliche Museum Berlin, origin: Tell Halaf (ancient Guzana), Syria. 10th-9th century BC.

They are mentioned in the Enûma Eliš, the region's creation myth that emerged between 2000 and 1000 BCE and of which the oldest surviving text is commonly thought to have been created in 1100 BCE

Atargatis is a Syrian chief goddess of protection and fertility who is associated with lions, doves, and fish. She is also, and perhaps more accurately, known as Ataratheh, and by the Greeks is also given the name Derketo. The earliest mentions of her in writing are the Lydiaca by Xanthus and the Persica by Ctesias. Both men are from the 5th century BCE and both their works only survive in fragments; it is through references to their works by later writers that the larger parts of their texts remain somewhat preserved. Mnaseas claims to cite Xanthus on a story that Atargatis, as a human, had a son named Ichthys ("ἰχθύς", "fish") and that the both of them were caught by Mopsus and placed in the lake by Ashkelon to be eaten alive by the fish there as punishment for Atargatis's hybris. Ctesias is the source of Diodorus Siculus's story that Atargatis angered Astarte and out of revenge she made her fall in love with Caystrus, a priest of Astarte. A daughter, Semiramis is born from this. Ashamed, Atargatis leaves her child, kills Caystrus, and plunges herself in the lake by Ashkelon to become a fish, though the transformation does not affect either her head or her entire upper body, depending on interpretation. Unlike the stories, the earliest known depictions of Atargatis as having a fishtail are not older than the 1st century BCE and most of the surviving material depicts her with legs.

Both Dagon and Atargatis

Another early mermaid concerns a fictionalization of a historical figure: Thessalonike, a half-sister of Alexander the Great. Historically, she was born either in 352 or 345 BCE, survived her brother when he died in 323 BCE, started a family and was eventually killed by one of her sons in 295 BCE. In the legend, she turned into a mermaid some time before Alexander's death. The earliest version of the Alexander Romance dates to the 3rd century CE, and among others tells of Alexander's search for the Fountain of Youth. The original version says only his companion found it, but later the story got adapted to specify that Alexander himself did get his hands on a flask filled with the water and brought it home. Depending on the version, Thessalonike drinks it or spills it by accident. Alexander subsequently curses her to become half woman and half fish, which she does not hold against him. Alternatively, he knowingly washes her hair with the water and when he later dies, she tries to commit suicide by jumping in the sea but is instead transformed into a mermaid. In any of the three scenarios, Thessalonike goes on to accost ships at sea with the question "Is Alexander the king alive?". If the answer is "He lives and reigns and conquers the world," she leaves the ship unharmed and in calm waters. Otherwise, she destroys ship and crew. A popular edition of this legend was penned down by Andreas Karkavitsas in 1899 in ''Words from the Prow. Sea Stories'', in which the wrong answer can be negated by providing the correct answer before Thessalonike attacks.

Eurynome Lamia Sybaris (Antoninus Liberalis, Metamorphoses 8, CE 100 and 300) Keto Scylla Triton Echidna Glaucus Acoetes Drakaina

In 1989, The Walt Disney Company released The Little Mermaid, an adaption of the Andersen tale. It placed the Ancient Greek Triton, complete with trident and golden palace, in the role of King of the Sea and father of the titular mermaid, who is named Ariel in Disney's work. Many details were altered to make the movie kinder than the fairytale, such as all the parts relating to souls and the bittersweet ending. One choice with lasting influence is the design of the witch, who is a regular mermaid in the original tale but one with an octopus-like lower body. For the movie, she is the only 'alternative mermaid' present and creatures like her are regularly referred to as sea witches since. However, Disney greatly expanded the movie's underwater diversity in additional The Little Mermaid media. The witch was given a sister in 2000 as the sequel to the 1989 movie needed a villain of its own, but prior a small army of octopus-based seafolk appeared in the 1992-1994 TV series, specifically in "Heroes" of Season 3. They are identified as octopans. The series also introduced manta ray-based seafolk in the form of Evil Manta and his son. Their species wasn't given a name, but with four episodes across all three seasons, Evil Manta was a regular presence. Lastly, a series of four The Little Mermaid comics were published in 1992. The first two, brought out in February and March, together hold one story, "Serpent-Teen". This story features eel-based seafolk, known as the moray, named after moray eels despite having the electrogenic abilities of electric eels. All of the alternative mermaids of Disney's The Little Mermaid are designed with full-body non-human skin colors, unlike the mermaids, and they are also all enemies of the mermaids. Nonetheless, Disney's The Little Mermaid is the biggest franchise to feature alternative mermaids.

Fiction
The Sea Lady: A Tissue of Moonshine presents two levels of reading, one literal and one metaphorical for depression-induced suicide. The titular Sea Lady is a mermaid, who came to life ages ago near Cyprus. Her eyes are sea-blue, her hair gold-blonde, and her skin white, while her tail that starts below the waist is consistently compared to a mackerel's. Like all of her kin, she has no soul or name (though the Sea Lady's human company names her Doris Thalassia Waters for the time she lives with them) and was formed as an immortal adult upon her spontaneous creation from water. Marrying a human would get a mermaid a soul, but at the cost of their immortality. The Sea Lady is familiar with human life, mostly through reading — human literature is extremely popular among the merfolk, even though they find humans pathetic for their desire to make themselves fit society. Prior to the story, in Tonga, Polynesia, the Sea Lady spots Harry Chatteris, a man from a family with titles but few resources, who is of such talent that the family hands him everything in hopes he'll restore their lost name in society. The Sea Lady senses that he is unhappy with his obligations and sets out to acquire him for herself, not to marry him, but to kill him as her way of giving him "better dreams". Her one mistake is assuming him to be single, but the feelings of Adeline Glendower, a woman who had barely a youth due to her mother's death and her father's abusive and demanding ways, are of no interest to her, as she considers humans in general fake. Following Chatteris to Folkestone, England in 1899, she assumes him to be one of the children of Mrs. Bunting and manipulates herself into the woman's matronly favor. Her arrival is met with shock, but also interest and charity, and she soon has a place within the family as another guest. When Chatteris returns for Glendower, another guest of the Buntings, the Sea Lady latches onto him emotionally and doesn't let go. She only reveals her intents to Melville, another guest, but subtly enough that Melville doesn't dare act out of fear he's wrong. He leaves to London, only to return to Folkestone when Chatteris breaks off his engagement with Glendower, the Sea Lady is kicked out of the Bunting's residence, and Melville is the only one thought to have a chance to fix the matter. He talks to both Glendower and Chatteris, with Chatteris confiding that his love for Glendower cannot be put into words but that his whole life is made for him. He knows choosing the Sea Lady means death and vows to return to Glendower tomorrow morning and step back into the enviable life laid out for him. At the time, it is truth, but hours after Melville has departed, Chatteris franctically goes after the other choice, dressing himself up nicely and visiting the Sea Lady. He carries her off to the sea while she laughs and he shows no emotion. How she drowned him, viciously or gentle, is speculation left to the survivors.

Monster High
The Monster High cast of mermaids includes Sirena Von Boo and her mother as well as Rider and Finn. There's also a Create-A-Monster set shaped like a mermaid, but marketed as a siren. Similarly, while presented as a siren, Madison Fear has the form of a legged mermaid. And while they aren't characters, Monster High has introduced two cilophyte-like creatures in the webisode "Falling Spirits".

Mermaids in Monster High follow the post-2000 exploration of mermaid designs that assign fish traits to the upper half too. All three mermaids and the cilophytelike backgrounders have the same skin covering their entire body.