Deep One (Lovecraft Cthulhu mythos)

Deep Ones

(Cthulhu mythos)


The Deep Ones species is a notable part of the Cthulhu Mythos created by horror writer H.P. Lovecraft. The Deep Ones’ main appearance is in the novella The Shadow over Innmsouth, which was published in 1931.

There’s no “canonical” look for Deep Ones. This article uses a semi-random selection of Internet images as illustrations, to provide examples of the variety of takes on the literary descriptions.


  • Marital Status: Probably inapplicable in all cases.
  • Known Relatives: Varies.
  • Group Affiliation: Member of the Deep Ones, ally of Human Worshippers of the Great Old Ones, servant of the Great Old Ones.
  • Base Of Operations: Various undersea cities around the world.
  • Height: 5’ 6” Weight: ? lbs. Age: Tens of thousands of years.
  • Eyes: Greenish-grey Hair: None


Powers and Abilities

The Deep Ones are a race of undersea-dwelling amphibious humanoids with pale, shiny, hairless skin. They have large, bulbous eyes, long arms, stubby legs and clawed and webbed hands and feet. Their skin and eyes are a pale greenish-grey, though their bellies are white.

They have scaly ridges on their backs, jaws, hips and joints and over their prominent gill slits.

They can communicate telepathically with one another over long distances. Their audible speech has been described as consisting of “hoarse barkings and loose-syllabled croakings”.

The Deep Ones prefer salt water to fresh, but can survive in either. Their usual habitat is deep in the ocean (hence their name). Despite being primarily marine creatures, they can come to the surface and can survive on land for some time. All Deep Ones are immortal — none die except by accident or violence.


They serve the Great Old Ones known as Father Dagon  and Mother Hydra , as well as Great Cthulhu. They are opposed by the Elder Gods, the enemies of the Great Old Ones, whose powerful magic can keep them in check.

The Deep Ones live in great cities built on the ocean floor. The only one known by name and location is Y’ha-nthlei, off the coast of Massachusetts. The U.S. Navy learned of its existence and torpedoed it in 1928, killing a number of the inhabitants. But the survivors have undoubtedly rebuilt it by now. Their worldwide population is said to number in the millions.

The Deep Ones sometimes strike bargains with humans in remote coastal or island communities. The deal is that the aquatic species provides plentiful fishing and gold in the form of strangely-formed jewelry. In return, the land-dwellers offer ritual carvings, human sacrifices and a promise of “mixing” — the mating of humans with Deep Ones.



The Deep One hybrid offspring are born with the appearance of normal humans. However, most individuals will eventually transform into full-fledged Deep Ones, gaining immortality — by default — only when the transformation is complete.

The age at which the process of transformation begins can vary from adolescence to middle age, but once begun it always follows the same general pattern.

As the hybrid gets older, they begin to take 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, membranes grow between the fingers and toes, the feet grow large and frog-like and the neck develops folds which later become gills. The individual also develops an unpleasant fishy body-odor.

When the hybrid becomes too obviously non-human, it is hidden away from outsiders. The metamorphosis may take years or only a few months. It is often traumatic, driving the hybrid to seek refuge from the pain in alcohol or drugs. It may sometimes even result in outright mental breakdown if the individual has previously been unaware of his or her hybrid nature and has never had any advance warning of what to expect.

A crouching Deep One under the Moon

When the process is finally complete they will be gripped by an overwhelming compulsion to slip away into the sea and go to live with the Deep Ones forever in one of their undersea cities.

In about 10% of cases the metamorphosis remains incomplete and the hybrid becomes trapped in a half-human state, forced to remain on land and condemned to eventually die of old age.


The Deep Ones appear to have some knowledge of Ritual Magic. But it seems to be used mainly to produce unspectacular results such as mimicking Animal Control in order to control pet shoggoths  and divert fish into the nets of their human associates.

Sorcerer-priests of the Deep One religion probably have far greater knowledge than most, used for things like directly communing with the Great Old Ones.

All Deep Ones are repelled by certain occult symbols which represent the Elder Gods who oppose their own deities. These include the triskelion or three-armed swastika (and possibly the four-armed swastika as well) and the Elder Sign, a kind of distorted pentagram with an eye at the centre.


Their level of technology is unknown, as none of their undersea cities have ever actually been seen. Their ability to produce gold jewelry in significant quantities suggests that they can somehow mine, smelt and refine ore despite the impossibility of making fire to heat a forge underwater under normal circumstances.

Perhaps their cities include factory complexes which are contained in watertight buildings filled with air, in order to overcome this problem.

The Deep Ones have claimed to be able to wipe out humanity with little effort if the mood should take them. However, these claims were made in the early 17th Century, when this would have been a much less challenging undertaking than it would be today.

The most destructive actions they’re actually known to have taken were limited to massacring a few hundred New England townspeople and causing the disappearance of a few fishing trawlers. Maybe they just talk a good fight… or not.


In the early 19th Century, the isolated fishing port of Innsmouth, Massachusetts, was mired in deep-rooted economic and demographic decline. Its long-term prospects were very bleak.

Thus, some of the desperate townspeople listened, and a few even believed, when Captain Obed Marsh told them of how, during his trading voyages to the Pacific islands, he had learned of odd rituals. For over 200 years the natives of one particular island had secretly been worshipping the Deep Ones, immortal amphibious beings who dwelt beneath the seas of the world. They offered these ritual carvings and human sacrifices.

In return, these beings gave the natives plentiful fishing and gifts of strange golden jewelry. After a time the Deep Ones had begun to demand that the natives should also mate with them to produce hybrid offspring, who would eventually metamorphose into full-fledged Deep Ones and take to the sea to join the others in the depths.

Within a few generations the island had come to populated almost entirely by such hybrids.

The natives had eventually been massacred by their neighbours on other nearby islands when their secrets had finally been found out. But before then Obed Marsh had been initiated into the cult of the Deep Ones. Now he sought to establish it in his home town.

Turning toward the sea

Marsh and his new followers began by running the local clergymen out of town or arranging their disappearance. Then they started rowing out to nearby Devil Reef at night to perform strange and sinister ceremonies on a regular basis.

Before long, strangely proportioned humanoid shapes could be glimpsed from a distance emerging from the sea to join them and eventually disappearing beneath it again. After this some of the young men of Innsmouth began dropping out of sight, never to be heard from again.

A Deep One with some draped seaweed

Marsh and his followers were soon to be seen in possession of strange golden jewelry whose origins they refused to discuss. Meanwhile the quantity of fish being caught by the townspeople went from meagre to abundant. Fishermen from neighbouring communities who tried to muscle in on Innsmouth fishing grounds after hearing of their abundant catches disappeared at sea without a trace.

Before long, Marsh and his followers had openly started their own sinister religion, the Esoteric Order of Dagon. It became the only religion tolerated in Innsmouth.


In 1846, those of the townspeople who were not prepared either to actively participate in what was going on or to continue looking the other way attempted to root out the evil from their midst. They arrested and imprisoned Marsh and his followers.

Before they could decide what to do with them, the Deep Ones emerged from the sea in force to find out why their worshippers had suddenly ceased to offer them sacrifices. Half of the townspeople were massacred and the survivors became the cowed subjects of Obed Marsh and his inner circle, forced to begin intermarrying with the Deep Ones to produce hybrid offspring.

Marsh himself took the lead in this process, taking a Deep One as his second wife and begetting children by her before his death. Anyone who was considered disloyal to the cult or considered likely to betray the secrets of Innsmouth to outsiders was taken for sacrifice.

By the early 20th Century, most of the population of Innsmouth (by then less than 400 strong) were secretly hybrids. They lived out seemingly ordinary lives on the surface in their early years while calmly waiting for the metamorphosis that would eventually allow them to begin eternal lives beneath the sea.

Deep One character design sheet

A few hybrids had also been born in other nearby New England communities whose people had occasionally intermarried with the inhabitants of Innsmouth over the years. Most of these appear to have remained unaware of their true heritage until their metamorphosis began.

The Deep Ones were apparently making leisurely plans for some kind of hostile action against the wider surface world which would have involved the deployment of shoggoths (shapeshifting entities which are normally formless but can assume whatever forms their masters direct) under their control.


In 1927 a tourist named Robert Olmstead, a keen amateur antiquarian, came to Innsmouth in order to see its wide selection of decaying old buildings. He ended up discovering the secrets of the town and barely escaped with his life. He eventually managed to convince the Federal authorities of the truth and in 1928 the U.S. military raided the town.

The inhabitants were rounded up and sent to secret prisons. A submarine subsequently located and torpedoed the Deep One city of Y’ha-nthlei beneath Devil Reef.

A number of journalists and civil rights activists who subsequently protested at the mass internment of the people of Innsmouth without trial were taken to see the horrible hybrid prisoners for themselves. After that they agreed to remain silent.

In a bitter irony, a few years later Robert Olmstead learned that he himself was a hybrid, being descended through his mother from Obed Marsh. His initial horror at the idea gradually changed to acceptance as his own metamorphosis began and his personality started to change as a result.

He eventually decided that he would be quite happy living forever beneath the sea. He began making plans to break a cousin who was even further transformed than himself from the asylum where he was being confined and take him with him.


Not really fleshed out in much detail. The Deep Ones could run the gamut of human personality types for all we know. Stereotyping would have to portray them as cold and unemotional, of course. They certainly appear to be fairly uncommunicative toward humans, even their own allies, but seem rather more sociable among their own kind.

Their motive for seeking to interbreed with humans appears to be a straightforward desire to extend their influence and the cult of the Great Old Ones in the surface world rather than because they find humans particularly attractive. Very likely they consider us as hideous as we consider them.

Their wish for human sacrifice is probably motivated purely by the desire to curry favour with the Great Old Ones through arranging it, rather than by their deriving an ego boost or any direct supernatural benefit for themselves from it.

Familial ties

Family is clearly important to the Deep Ones. Individuals who had been born on land as hybrids often returned to the places of their early lives to interact with their descendants. When Robert Olmstead began to undergo his metamorphosis he was telepathically visited in his dreams by his grandmother and great-great grandmother.

Both welcomed him and encouraged him to save his cousin from confinement in the asylum so they could join the Deep Ones together. Though Olmstead had brought the wrath of the surface men upon the inhabitants of Y’ha-nthlei and Innsmouth, he was told that his penance would not be a heavy one.

This trait may also extend to their sinister religious practices. Although they ultimately serve Great Old Ones such as Cthulhu, the more immediate day-to-day focus of their religion seems to be on ancestor worship.

This is most evident in the most frequent object of their prayers, the beings known as Father Dagon and Mother Hydra. According to some speculation these may merely be extremely ancient Deep Ones who have grown to enormous size over the millennia rather than true Great Old Ones.

Marvel Universe History

The history of the Deep Ones before the last few hundred years is entirely unrevealed. But they’ve probably been around for hundreds of thousands of years at least. They could be creations of the Celestials like the Eternals and Deviants. Or the Great Old Ones could have mutated them into being from human stock long ago.

Whatever their origins, they probably resented the water-breathing humanoid races of Atlantis and Lemuria as trespassers in their domain in the early days. The fact that neither side has exterminated the other over the millennia since then would seem to imply that they learned how to get along in the end, though.

In the DC Universe, they might even have become allies of convenience during the Invasion!  when the Gil’dishpan came marauding by.

Or maybe Poseidon-Neptune just threatened dire reprisals against the Deep Ones if they harmed his worshippers and they chose not to force the issue.

The wicked and the divine

The various references to the enmity between the Great Old Ones and the Elder Gods are usually taken to refer only to the group of cosmic beings collectively known by the latter name.

But they might also refer to the now largely extinct race of primordial beings of the same name who were native to Marvel Earth. The most prominent out of the handful still alive today is the serpent-god Set.

In that case, the attitude of the Deep Ones towards his worshippers in Lemuria is an interesting field for speculation. The Elder Gods of Earth were far older than Cthulhu (who is comparatively young by the standards of the Great Old Ones). They would therefore have been likely to regard the extraterrestrial being as an upstart trespasser in their rightful domain.

Set himself is hardly on good terms with any of the other surviving Elder Gods and has no feeing of solidarity with them. But he’d still be more likely to see Cthulhu as a rival rather than as a potential ally. So it’s probable that their respective worshippers are bitter enemies despite how much the two murderous cults have in common.

Undersea wars

The Deep Ones might even have given the Sub-Mariner and company some help against Ghaur and Llyra during Atlantis Attacks , on the basis that the enemy of their enemy is their friend. Who knows, they might have been doing the same thing for millennia. Maybe they helped out King Kull of Valusia in his battles with the Serpent Men back in the day as well.

I could even envision some variation on Atlantis Attacks (Y’ha-nthlei Yrlsquo;ha-ttacks?). The Lemurians manage to open a way for Set to return to this dimension just as the Deep Ones manage to awaken Cthulhu in R’lyeh. All Thor and Atum have to do is watch from the sidelines as they decide the Earth and the Universe aren’t big enough for both of them and end up destroying each other.

One also wonders if these practiced infiltrators have ever been infiltrated themselves. The Manhunter Androids and Dire Wraiths have shown up in places that are just as unlikely before now. And the now-extinct Serpent Men were shapeshifters too.

Deep One concept art

Obviously, their abhorrence of swastika-like symbols means that if you’re running a campaign set in the Golden Age they aren’t very likely to show up on the side of the Nazis! Maybe the Sub-Mariner and U-Man once had to join forces against a fiendish Deep One plot.

Any of the ancient immortals of the surface world might have encountered them long before now. One can imagine Vandal Savage and the Immortal Man calling a truce in their long struggle to fight against the common threat they posed, for example.

What long-term goal, if any, they’re actually working towards by seeking to increase their numbers and their influence in the surface world is unknown. Given that their immortality will predispose them towards patience and taking a long-term view, there’s no particular reason to assume that their plans will reach fruition any time soon.

Game Stats — DC Heroes RPG

Tell me more about the game stats

Typical Deep One

Dex: 03 Str: 05 Bod: 05 Motivation: (?) Power Lust/Serve the Great Old Ones
Int: 03 Wil: 03 Min: 03 Occupation: (?) Minion of the Great Old Ones
Inf: 03 Aur: 03 Spi: 03 Resources (or Wealth): (?) 010
Init: 09 (11) HP: 010

Water Freedom: 05, Cold Immunity: 02, Systemic Antidote: 03, Regeneration: 01, Suspension: 10, Claws: 06, Swimming: 05, Full Vision: 01, Ultra Vision: 03, Shade: 03, Telepathy: 05, Aura of Fear*: 03

Bonuses and Limitations:

  • Systemic Antidote: Protects against disease as well as toxins.
  • Suspension: This Power is Automatically Activated if Current BODY Condition drops to 0 or below due to damage from being kept out of water or from starvation and can only be used in this manner.
  • Telepathy: Has a Range of 20 APs. Only usable to communicate with other Deep Ones or Human/Deep One Hybrids whose metamorphosis into full-fledged Deep Ones has begun. The sender must concentrate on reaching a specific individual and the recipient must not be actively thinking of anything other than communicating (he must either be similarly concentrating or be asleep and so not consciously thinking at all).
  • Aura of Fear: Power Always On. Only affects land-dwelling animal life.

Artist (Jeweler): 04, Charisma (Intimidation): 05, Occultist (Occult Knowledge, Ritual Magic): 04, Weaponry (Melee Weapons): 03

Immortal, Scholar (Worship Rituals of the Great Old Ones), Area Knowledge: City (the undersea city where they live), Area Knowledge: Neighborhood (the nearest surface community where human worshippers of the Great Old Ones live).

Powerful Connection: Low Level (Great Old Ones), Connection: High Level (Human Worshippers of the Great Old Ones).

Strange Appearance, Loss Vulnerability (loses 1 AP from all Physical Attributes for each day spent without being at least briefly immersed in water), Misc: The large, splayed feet of a Deep One make it very clumsy on dry land, preventing it from running and limiting its land movement speed to only 1 AP., SIF (of some occult symbols), Enemy (Elder Gods), Enemy (U.S. government and military [and probably the governments and militaries of other NATO member-states as well]).

Optional Drawbacks:
Enemy (S.H.I.E.L.D.), Enemy (Lemurian and Human Worshippers of Set), Enemy (Barbarian Hordes of Attuma).

If expecting a fight, Deep Ones will likely carry the following:

  • Trident [BODY 07, EV 04].
  • Shortsword [BODY 07, EV 03].

By Hominid71 (but largely adapted from stats given in GURPS Infinite Worlds , by Kenneth Hite, Steve Jackson and John M. Ford).

Source of Character: The Cthulhu Mythos story The Shadow Over Innsmouth by H. P. Lovecraft (1931).

Helper(s): Wikipedia, Roy Cowan, Capita Senyera.