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You may wish to consult Sea Devil (disambiguation) for other, similarly-named pages.

The Sea Devils, or Sea-Devils, (PROSE: Doctor Who and the Sea-Devils) also called ocean demons, (TV: Legend of the Sea Devils) the Aquatic Silurians (PROSE: Blood Heat) and Reptilia Sapiens (AUDIO: Tidal Wave), were amphibious Earth reptiles. Like their land-based cousins, the Silurians, they lived in prehistoric times in a scientifically-advanced civilisation.

As their aquatic colonies awoke from suspended animation, these one-time rulers of the Earth attempted to reclaim their planet, leading to conflict with the new rulers: humankind.


An advanced sub-species of Sea Devil lived on the Raven Peninsula. (COMIC: Clara Oswald and the School of Death)

The Sea Devils were related to the Silurians, though they were genetically divergent enough to create problems for the offspring of such matings. (PROSE: The Scales of Injustice)

Like the Silurians, variations existed among the Sea Devils with different subspecies and appearances. Sea Devils typically looked somewhat like humanoid turtles or plesiosaurs. They had beak-like mouths, large eyes, two fins on their head and long necks. They had three webbed digits on their hands and feet. Their skin tones came in a variety of shades, including green, blue and orange. They were much tougher than humans, since they needed to survive the crushing depths of the ocean. Sea Devils communicated in a language like sonar, but they could speak human languages in a whispering, rasping voice. (TV: The Sea Devils) A Sea Devil's skin was slimy to the touch. (PROSE: The Silurian Gift)

One group of Sea Devil warriors, which appeared at Sea Base 4, were notably distinguished by their silver skin and their lack of head fins. (TV: Warriors of the Deep)

Another subspecies of Sea Devil, suggested by the Twelfth Doctor to be a "warrior-class", were larger, faster, and stronger than those that he was familiar with. Their muscular bodies sported dark green skin, small red eyes, a pronounced jaw, and a large tail. They lived on the Raven Peninsula. They could communicate using a form of sound-based telepathy and could use this ability as a weapon by producing a deadly sonic scream. (COMIC: Clara Oswald and the School of Death)

There also existed a class of Sea Devils who were much smaller, about the size of an infant human, that could merge with a human host, creating a human-Sea Devil hybrid but with the Sea Devil's psyche dominating its host. They possessed the sound-based abilities of their warrior-class counterparts but also displayed potent psionic powers, specifically telekinesis. The Twelfth Doctor explained that this was a side effect of two minds merging into one. (COMIC: Clara Oswald and the School of Death)


The Sea Devils worshipped the Great Old One known as Dagon as their god. (PROSE: All-Consuming Fire) They were determined to retake the planet from the humans. They held an unwavering view that, as the original rulers, it would always be their right to do so. However, they were willing to make peace with humans, but they quickly changed their minds when they were under attack from the surface. (TV: The Sea Devils) Even though encounters between the Sea Devils and humanity often devolved into conflict in the 20th and 21st centuries as they battled for control of Earth, (COMIC: Clara Oswald and the School of Death, et. al) the Thirteenth Doctor noted that the Sea Devils were largely peacefully, fighting only if they believed it to be needed (TV: Legend of the Sea Devils) or if they had been manipulated. (TV: The Sea Devils)

As such, the Doctor was surprised to meet one Sea Devil chief who prepared for mass-human genocide before even attempting peace. She reasoned that he was simply "the bad egg" of his kind. (TV: Legend of the Sea Devils)


The Sea Devils were more advanced than the humans of the 20th century when they went into hibernation. They had colonies around the world, each filled with thousands of Sea Devils. (TV: The Sea Devils) The colonies could be awakened en masse through the use of a sonic signal. (TV: The Sea Devils) They built their underwater colonies inside caves. One base, located near a sea-fort, had simple grey-black-coloured walls, (TV: The Sea Devils) while another appeared to be carved into the rock, and was covered in algae and seaweed. (TV: Warriors of the Deep)

They also used special orange capsules to transport land-dwelling creatures. (TV: The Sea Devils)

A Sea Devil tracking radar (TV: The Sea Devils)

The Sea Devils had stockpiles of weapons in these bases. They typically used small, round, side arms. (TV: The Sea Devils) During their invasion of Sea Base 4, they made use of a larger version of the device to cut through the doors. (TV: Warriors of the Deep) The group that commandeered the ship of Sin Ji-Hun wielded swords instead, with their captain using a special, technologically advanced blade with a glowing section down the centre that could inject a lethal poison into those it wounded. (TV: Legend of the Sea Devil)

The Sea Devils which attacked HMS Seaspite wore gauze-like dresses. (TV: The Sea Devils) The Sea Devils warriors in the 2084 invasion wore thick black armour reminiscent of samurai armour. (TV: Warriors of the Deep)

The Sea Devils that attacked Ravenscaur Island had an enormous underground colony located in a network of caves that artificially reproduced the environment and climate of prehistoric Earth, indicating they had advanced terraforming and environmental technology.

They had colossal war machines that were shaped like giant metal spheres with tentacles that could pierce through the hull of a human battleship easily.

Sea Devils also had large submarines heavily armed with laser armaments that could easily outmatch an aircraft carrier with its speed and firepower.

A fearsome piece of technology they possessed was sonic destructors. These were enormous tower-like structures that produced sonic pulses capable of sinking an entire island by causing intense earthquakes. (COMIC: Clara Oswald and the School of Death)



The Sea Devils ruled the Earth when humans were apes, just as the Silurians did. (TV: The Sea Devils) Both the Silurian and Sea Devil races were led by the Triad, their "custodians". (TV: Warriors of the Deep) While one Sea Devil chief, whom the Thirteenth Doctor wrote off as a zealot, claimed the Earth had been covered "in glorious aqua" during the age of his kind, (TV: Legend of the Sea Devils) the Sea Devils and Silurians lived alongside each other, (TV: Warriors of the Deep) with the Silurians ruling over warm landmasses (PROSE: Blood Heat, TV: The Hungry Earth) while their underwater cousins lived within the seas. (TV: Warriors of the Deep)

Sea Devils hibernate (TV: Warriors of the Deep)

When the Moon approached Earth, (TV: Doctor Who and the Silurians) the Silurian and Sea Devil scientists calculated a great catastrophe in which "all life" would be wiped out (TV: Doctor Who and the Silurians, The Sea Devils) by the Moon "sweep[ing] by Earth" (PROSE: Doctor Who and the Cave-Monsters) and drawing away the atmosphere. (TV: Doctor Who and the Silurians) The Third Doctor repeated the claim to Marc Marshall that the Silurians built the shelters when they thought the planet would "suck away" Earth's atmosphere as it rushed by. (PROSE: The Scales of Injustice)

Conversely, the Fifth Doctor recalled that the Silurian astronomers predicted that Earth was about to be "struck" by the planet at the time, (PROSE: Warriors of the Deep) and the Eleventh Doctor described the trajectory of the planet the astronomers had predicted as a "crash course". (TV: Cold Blood) The catastrophe did not happen as predicted, and the Sea Devils remained inside their hibernation units. During millions of years of hibernation, the reactivation machinery of the hibernation units deteriorated. (TV: The Sea Devils)


16th century[]

A Sea Devil captured by pirates. (COMIC: Devil of the Deep)

A lone Sea Devil scientist was prematurely awakened around the late 16th century due to a defective hibernator, proceeding to study how the world had changed during his sleep. After ten years, the Sea Devil rescued and befriended a human, Diego de Columba of Cordoba, who had washed up on the beach. Unfortunately, the Sea Devil was later captured by pirates, one of whom inadvertently activated his device which called a creature to awake from under the sea, proceeding to destroy the pirates' ship. Diego presumed the Sea Devil to have perished with the pirates. (COMIC: Devil of the Deep)

Also in the early 16th century, a zealot Chief Sea Devil became active alongside his crew in the seas of China. Capturing the ship of the "great captain" Sin Ji-Hun in order to "strike fear" into the hearts of the "land crawlers", he and his band became fearsome pirate. The Chief Sea Devil sought a particular gemstone, the Keystone, actually of Sea Devil origin, which he wanted to use to flood the entire Earth, wiping out humanity. However, Ji-Hun had managed to sneak the Keystone off the ship before the Sea Devils captured it, and his second-in-command Lei Bao was eventually able to use the Keystone himself to freeze the Chief Sea Devil in time, turning him into a statue on the shore. His crew returned to hibernation, awaiting his return. (TV: Legend of the Sea Devils)

19th century[]

In 1807, Madam Ching, a notorious pirate who was looking for the lost treasure of the Flor de la Mar, travelled to the small Chinese village where the petrified Chief Sea Devil pirate was still watched over by the descendants of Lei Bao. Misunderstanding the legends and believing a map to the treasure was hidden within the statue, she accidentally released the Chief Sea Devil, who slaughtered the village and called his crew out of hibernation. However, the Thirteenth Doctor and her companions teamed up with Madam Ching, as well as Sin Ji-Hun, whom the Sea Devils had kept locked in a living death for all these centuries as a punishment for tricking them, to stop his plan. Shortly after Ji-Hun stabbed the Chief Sea Devil to death in a duel, he and the Doctor managed to rig the pirate Sea Devils' base to explode, killing them all, destroying the Keystone, and stopping the Chief Sea Devil's plan to flood the Earth from coming to pass. (TV: Legend of the Sea Devils)

20th century[]

Sea Devils emerge from their hibernation units in 1909. (COMIC: Clara Oswald and the School of Death)

In 1909, a group of Sea Devil woke up beneath Raven Peninsula. They used terraforming technology to create an earthquake which separated the peninsula from the main land. Ravenscaur became known as Raven's Isle. The Sea Devils infiltrated the school and village on the island by turning the humans into Sea Devils. (COMIC: Clara Oswald and the School of Death)

In 1972 or 1982, (COMIC: Clara Oswald and the School of Death) a group of Sea Devils hibernating beneath the English Channel were awoken by the Master. He attempted to persuade them to reclaim the planet from the human race. Despite the Third Doctor's efforts to convince them otherwise, hostilities escalated when Private Secretary Walker ordered the Royal Navy to attack the base, and the Sea Devils decided to go to war with the humans. However, before they could use the Master's sonar device to reactivate more bases, the Doctor blew up their base by overloading the devices by reversing the polarity of the neutron flow, preventing the war between humans and Sea Devils from starting. (TV: The Sea Devils)

In 1983, Sarah Jane Smith and K9, visiting Warren Martyn's archaeological expedition in Egypt, discovered an underground city of Silurians and Sea Devils. Sarah Jane opened diplomatic relations with them. On her return to England, she contacted the Brigadier, who wished to make amends for his earlier mistakes. (COMIC: City of Devils)

Early 21st century[]

This section's awfully stubby.

Information from AUDIO: Tidal Wave

Jo Grant and Petronella Osgood encounter Sea Devil at Project Charybdis. (AUDIO: Tidal Wave)

In the early 21st century, a colony of both Silurians and Sea Devils were discovered under the South Pole. After a corrupt businessman attempted to blackmail them into providing him with a unique energy source, they revolted, with the Sea Devils launching an attack. They were forced back into hibernation by the Eleventh Doctor, who collapsed the crevice leading to their colony afterwards. (PROSE: The Silurian Gift)

In 2015, the Sea Devils at Ravenscaur School were discovered by Christel Dean who alerted Clara Oswald and the Twelfth Doctor to their presence. When the Sea Devils declared open war on humanity, the Doctor managed to turn their sonic devastators back on them, wiping them out. (COMIC: Clara Oswald and the School of Death) Sometime before the shutdown of UNIT, a group of Sea Devils had attacked a classified military base in South Wales, leaving Brigadier Winifred Bambera missing in action. (PROSE: At Childhood's End)

Late 21st century[]

A colony of Sea Devils are awoken by the Silurians in 2084. (TV: Warriors of the Deep)

A colony of Sea Devils were awoken in 2084 by a group of Silurians who believed peace with humanity was impossible. Alongside a Myrka, the Sea Devils were sent as shock troops to invade Sea Base 4 to ignite the war the base had been built to fight in. Although they were better prepared, they were all killed by the Hexachromite gas used by the Fifth Doctor, who proclaimed that "there should have been another way" as he looked over the remains of the Silurians and Sea Devils. (TV: Warriors of the Deep)


By the 26th century, the inter-species conflicts appeared to have come to an end. Silurians and Sea Devils were accepted into Earth society, and the term "Earth Reptile" was apparently popularised among humans. (PROSE: Love and War)

Around the 26th century, a number of Sea Devils and humans colonised the planet Chosan, which was being attacked by Calabraxian terrorists. The Earth Reptile Council asked the Braxiatel Collection for aid. They sent Bernice Summerfield. She found the ocean planet held a sentient protein in the waters which had began to infect the water-dwelling Sea Devils. The entities attempted to possess the Sea Devils and use them as an army against the humans but faced difficulty in integrating themselves into the host's biology. This led to mutations. They took the Sea Devil Lurnix as a host. They tried to have Lurnix lower the security grid and infect all the Sea Devils for an army. However, Bernice Summerfield evacuated the colony and detonated a bomb at Chosan, ending that threat. The Sea Devils were forced to abandon the Chosan colony due to the continuing threat. (AUDIO: The Poison Seas)

Jo Grant hallucinates about a Sea Devil. (TV: Frontier in Space)

In the 30th century, the Earth Reptiles were part of the Earth Empire and were considered full members of that government as an Earthborn species. (PROSE: So Vile a Sin) In the 32nd century, it became illegal to trade in Earth Reptile pituitary analogue extract on the planet Dramos. (PROSE: Burning Heart)

In the 101st century, the Earth Reptiles were part of the Union. (PROSE: The Crystal Bucephalus)

Undated events[]

A Sea Devil in the TARDIS. (GAME: Destiny of the Doctors)

During the Last Great Time War, a Sea Devil was imprisoned by an unknown force. (COMIC: The Forgotten) A group of Sea Devils were imprisoned in the TARDIS by the Master. (GAME: Destiny of the Doctors) A Sea Devil was worth an unidentified amount of points in the I-Spyder Book of Earth Creatures if it was spotted. (PROSE: The Last Dodo)

A drawing of a Sea Devil from an Anubian book. (TV: Curse of Anubis)

As shown in the Anubian Book of Deliverance, the Anubians attacked the Sea Devils. (TV: Curse of Anubis)

A Sea Devil visited the beach on Beachelguese with a Silurian and a Macra. (COMIC: Surfshock)

Alternate histories[]

In one alternative version of the 1990s, the Doctor having died during the Wenley Moor incident, the Silurians ruled Earth unchecked while the Sea Devils served them as underwater soldiers. (PROSE: Blood Heat)

In an alternate timeline created by the Black Guardian where the First Doctor never left Gallifrey and became Lord President, the Sea Devils and the Silurians fought over the Earth along with several species of alien invaders. This timeline was destroyed when the Seventh Doctor retrieved the Key to Time. (COMIC: Time & Time Again)

In an alternate timeline created by a paradox caused by an encounter between the Thirteenth and Tenth Doctors, the Skithra awoke the Sea Devils in the Raven Peninsula in 1903 to conquer Earth on their behalf. By 2020, the Sea Devils ruled Earth. This timeline was erased when a Skithra Queen and Rose Tyler, who had been brought back in time by the two Doctors, killed the Skithra drones before they awoke the Sea Devils in 1903. (COMIC: Alternating Current)

In an alternate dimension in which the Doctor's adventures existed as a fictional TV show called Doctor Who, a fan dressed as a Sea Devil was present at a Doctor Who convention which the Eleventh Doctor visited with Ally in 2013. (COMIC: The Girl Who Loved Doctor Who)

The Sea Devils of Mondas[]

Main article: Sea Devil (Mondasian)

The planet Mondas had lifeforms identical to Sea Devils. (COMIC: The Hungry Sea)

Other references[]

In the video game Happy Deathday, played by Izzy Sinclair on the Time-Space Visualiser, a Sea Devil was among a host of "every single enemy" that the Doctor had ever defeated, who were assembled by the Beige Guardian and pitted against the Doctor's first eight incarnations. (COMIC: Happy Deathday)

Behind the scenes[]

A depiction of a Sea Devil and Silurian in Scarlet Traces: The Great Game.