- "I have guarded the Trident against false kings since the beginning, and for a thousand years, I have seen the greatest champions try and fail."
- ―The Karathen to Arthur Curry[src]
The Karathen is a colossal, sentient sea creature, and one of the most powerful beings on Earth. She has guarded the Trident of Atlan in the Hidden Sea for millennia, and later assists Aquaman with his quest to prevent war between the surface world and the sea, fighting on his side against Ocean Master in the War for Atlantis.
- "Down here, we have a legend about the Karathen, an ancient sea monster so powerful that even King Atlan himself feared it. So, he imprisoned it in the depths of the ocean. And in that abyss, the creature bides its time waiting to rise again."
- ―Orm Marius to Arthur Curry[src]
Long thought to be merely a creature of legend, many Atlanteans believed that the Karathen served as a guardian beast of the ocean who would one day rise up from the depths to signal Atlantis' uprising from its watery exile. In truth, however, she is real, having been found deep within a pit behind a waterfall in the Hidden Sea. She has fended off false claimants of the Trident of Atlan ever since Atlan's death. However, Arthur is able to convince her that he needs the trident to protect the people that he loves and the world of man. The Karathen relents to test his claim of ownership, but warns Arthur that she was only half of the initial trial, informing him if he should fail to grasp the trident the result wouldn't be pleasant.
Karathen resembles a colossal combination of a squid, a shrimp and a dragon.
An old, sombre and solemn soul, the Karathen spent many years in the service of King Atlan during his reign, and even unto his nomadic exile following the sinking of Atlantis. Thus, the Karathen, despite her ferocity, is a loyalist with incredible amounts of integrity. Choosing to honor the last will and testament of her long deceased confidante, she guards the Trident of Atlan in the Hidden Sea, and is willing to aid Atlan's heir in battle. While normally a taciturn creature, she can be roused to anger whenever a self-styled heroic showboat enters her den to claim her late leader and friend's trident. Moreover, the Karathen is an astute judge of character, and tests the worthiness of anyone willing to enter the Hidden Sea, and claim the trident.
When first meeting Aquaman, she, like the Atlanteans, was hostile towards him due to his mixed heritage, however, upon learning that he could communicate with her telepathically, she found herself taken aback by his profound sincerity, his depth of character, as well as him being the first since Atlan to ever understand and communicate with her. The Karathen gained a profound faith in this half-Atlantean, thereby allowing him to attempt to claim the trident, and even respecting Aquaman enough to warn him about what would happen should he fail to claim it. The Karathen shows signs of lamentation along with other emotions. Speaking with a somewhat sullen tone after Aquaman touches her mind with his marine telepathy, with her remembering in repine how the late king Atlan once had done the same long ago.
Powers and Abilities
- Superhuman strength: Karathen is a colossal sea monster with tremendous strength, allowing her to easily slap around Aquaman with her tentacles (with Atlanna, and later even Aquaman being unable to so much as get past her), to burst out of the seafloor in the Kingdom of the Brine, and to destroy several massive Atlantean warships with a single swipe.
- Superhuman reflexes: While Karathan possesses a normal general speed expected from a creature her size, her reflexes are extremely sharp, enough so to catch Aquaman in his attempt to retrieve the Trident of Atlan, completely outspeeding Aquaman with her tentacles and preventing him from even as much as touching the Trident despite his tremendous swimming speed.
- Nigh-invulnerability: Karathan is unbelievably durable, exponentially more than any high-born Atlantean. She shrugged off huge barrages of Atlantean firepower, withstood mighty attacks from both Atlanna and Aquaman, and even came into contact with molten lava, all with little to no stress and no apparent harm to herself. only firepower of immense scale is capable of causing harm even by the slightest and at most stagger her for a moment.
- Longevity: Karathen predated the sinking of Atlantis, and has guarded the Trident of Atlan for millennia in the Hidden Sea, seemingly without aging or weakening.
- Superhuman intelligence: Karathen, despite her monstrous appearance, is extremely intelligent and wise, due to her tremendous lifespan, with her being able to hold telepathic conversations with first Atlan, and later Aquaman. She is also an astute judge of character, as she could tell that Aquaman was truly selfless and loyal in his pursuit of the Atlantean throne.
- Clairvoyance: Karathen appears to possess a form of clairvoyance, as she was able to tell that Aquaman is only half-Atlantean merely by seeing him.
- Amphibious adaptation: Although spending most of her life underwater, Karathen can survive both underwater and on land, as witnessed when she reached the water surface to praise Aquaman.
- The Karathen was inspired by the Kaiju of Pacific Rim.
- The Karathen may be an adaptation of the sea creatures Topo or the Karaqan, both being titanic Kraken-like leviathans intelligent enough to hold telepathic conversation with Aquaman, or resist his marine telepathy outright.
- Karathen is two miles long according to VFX supervisor Jeff White. 
- The only moment the Karathen was ever harmed is in the Battle of the Brine, a Atlantis Fleet Carrier fired its Howitzer, hitting her and throwing arthur off, the pain is enough to stagger her for a moment.