The Deep Ones are a fictional species of ocean-dwelling humanoids, created by H. P. Lovecraft for his story Dagon, although not identified by name until the novella ''The Shadow Over Innsmouth'', in which Lovecraft presents them as having an affinity for mating with humans. A description is offered by the narrator of ''The Shadow Over Innsmouth'':

''"I think their predominant color was a greyish-green, though they had white bellies. They were mostly shiny and slippery, but the ridges of their backs were scaly. Their forms vaguely suggested the anthropoid, while their heads were the heads of fish, with prodigious bulging eyes that never closed. At the sides of their necks were palpitating gills, and their long paws were webbed. They hopped irregularly, sometimes on two legs and sometimes on four. I was somehow glad that they had no more than four limbs. Their croaking, baying voices, clearly used for articulate speech, held all the dark shades of expression which their staring faces lacked ... They were the blasphemous fish-frogs of the nameless design—living and horrible."''

Lovecraft's novella tells of how the Deep Ones entered a contract with the people of Innsmouth to keep the fish plentiful in their area, and provide them with a supply of gold artifacts of inhuman design. The Deep Ones are presented as worshipping the Cthulhu Mythos entity Father Dagon and his consort Mother Hydra.

The backstory of ''The Shadow over Innsmouth'' involves a bargain between Deep Ones and humans, in which the aquatic species provides plentiful fishing and gold in the form of strangely formed jewelry. In return, the land-dwellers give human sacrifices and a promise of "mixing"—the mating of humans with Deep Ones. Although the Deep One hybrid offspring are born with the appearance of a normal human being, the individual will eventually transform into a Deep One, gaining immortality—by default—only when the transformation is complete.

The transformation usually occurs when the individual reaches middle age. As the hybrid gets older, he or she begins to acquire the so-called "Innsmouth Look" as he or she takes on more and more attributes of the Deep One race: the ears shrink, the eyes bulge and become unblinking, the head narrows and gradually goes bald, the skin becomes scabrous as it changes into scales, and the neck develops folds which later become gills. When the hybrid becomes too obviously non-human, it is hidden away from outsiders. Eventually, however, the hybrid will be compelled to slip into the sea to live with the Deep Ones in one of their undersea cities.

All published appearances of the Deep Ones from before January 1, )-(95)}} are in the public domain in the US.

Some notable appearances include:

*Dagon (1919)
*The Shadow over Innsmouth (1931)

*RuneSword II (2001)

*[https://en.wikipedia.org/wiki/Deep_One Wikipedia]
*[https://lovecraft.fandom.com/wiki/Deep_Ones_in_Popular_Culture HP Lovecraft Wiki]
*[https://comicvine.gamespot.com/deep-ones/4060-58458/issues-cover/ ComicVine]
*Myths in Media Wiki
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