Dagon

Dagon is an antagonist in the Jujutsu Kaisen series. He was an unregistered special grade cursed spirit aligned with Mahito, Jogo, and Hanami. Dagon was born from the fear of water-based natural disasters and existed as a cursed womb until he evolved during the Shibuya Incident.

Appearance
As a cursed womb, Dagon had an appearance similar to an aquatic animal like an octopus. He's bright red with a circular-shaped head, big round eyes, and striped tentacles around his mouth opening. Dagon had two muscular arms with four fingers and a caterpillar-like body. He normally covered himself with a white cloth draped over his head and back.

In his evolved state, Dagon had a much taller, humanoid shape, similar to Hanami. His head changed to a shape reminiscent of an octopus with black dots on the top. He was mostly red, including the outer portions of his arms, thighs, hips, and chest. The inner sections of those areas of his body were tan. His midsection was black and he had wings on his lower back that allowed him to levitate.

Personality
In his cursed womb state where Dagon was essentially an infant curse, he was very docile, especially compared to Jogo and Hanami. He would remain on the sidelines through most of the operations and simply maintained the domain in their group's hideout. Dagon would devour people when called upon but wasn't nearly as active as his allies. He was most comfortable around his allies and appeared very shy and nervous when alone.

Dagon would silently follow his friends while in their company. Despite being capable of human speech, he only communicated through noises like "bwoo-hoo" and didn't participate in any conversations. However, Dagon cried out for help and called for his friends by name when he was in trouble. When he realized Hanami was already gone, Dagon was infuriated to the point where pure rage drove him to evolve from a cursed womb into a full-fledged cursed spirit.

As a powerful cursed spirit, Dagon gained a much more aggressive personality and took pride in his strength as a curse, far more reminiscent of Jogo, Hanami, and Mahito. His overall intelligence grew a great deal, so he spoke regularly and used tactics to overcome adversity.

Dagon's anger over Hanami's demise made him resentful of his enemies and didn't take kindly to being referred to as simply "cursed spirit", emphasizing that he and all his allies chose to bear names. While he did recognize that Naobito was a powerful opponent, he mocked Maki for being a weak and was irate when she taunted him back after surviving his attack.

Dagon ultimately underestimated his human opponents and tried to resist having his pride crushed when he was bested by Toji Fushiguro, a human with no cursed energy at all. Dagon admitted that he needed his domain's guaranteed hit to have any chance of winning and attempted to buy time. Even at the very end, Dagon tried to resist his fate, claiming the fight wasn't over just before being exorcised.

Abilities and Powers
Overall Skill Level: Dagon was a special grade curse with the dangerous ability to generate and control water. This made Dagon a great threat close to the level of his allies despite his lack of hostility while existing as a cursed womb. Even while docile, Dagon could easily dispatch dozens of weak non-sorcerers by using water to devour them all at once. However, he was vulnerable while alone however and couldn't stand up to strong sorcerers like Naobito Zenin.

Dagon was far more powerful in his evolved state in part due to his heightened intelligence and more physically imposing shape. He could generate water on such a scale that Maki claimed it far outclassed Max Elephant. Naobito and Nanami working together couldn't exorcise Dagon as quickly as it would be expected from two grade 1 sorcerers. Naobito, head of the Zenin clan at the time, recognized that Dagon had increased his cursed energy to immense levels and had access to a wide array of techniques. Dagon's jujutsu was only overcome by Naobito's speed until the cursed spirit created an opportunity to unleash his Domain Expansion.

Dagon's Domain Expansion included a can't-miss attack that quickly overwhelmed his trio of opponents. While Naobito was able to weather the initial storm, Dagon recognized his opponent's talent and used intelligent maneuvering to get around his defenses. After Megumi entered the fray and expanded a domain of his own, Dagon had to fight four-on-one without his domain's guaranteed hit. Maki and Naobito were unable to deal any significant damage while fighting Dagon together and the sorcerers had to resort to trying to flee the domain.

Immensely Enhanced Durability: Dagon's fully realized form is incredibly durable and difficult to damage, even for elite sorcerers. Alongside a flurry of several other attacks, Dagon suffered minimal damage from getting hit by Nanami's Ratio Technique, which forces critical hits. This left the sorcerer questioning if he dealt any damage at all and he felt as if Dagon had boundless health.

High Tactical Intellect: Dagon's overall intelligence matured exponentially when he evolved. When his jujutsu was overcome by his adversaries' speed, Dagon fled up high to avoid them. He recognized he couldn't directly overcome Naobito's speed so he distracted him with a technique activating hand sign, giving the curse enough opportunity to actually cast his domain.

Dagon accurately dedicated specific percentages of his domain's abilities to his targets and nearly eliminated all of his opponents. He was able to outmaneuver Naobito's Falling Blossom Emotion defense by using Death Swarm's endless shikigami to blow block his view before attacking. Once Dagon's can't-miss attack was neutralized by Megumi, he quickly changed strategy and focused on eliminating the competing domain. While Dagon initially misunderstood Megumi's intention, he eventually figured out Megumi was planning to use his domain to create a hole for everyone to escape. The four of them working together could never defeat Dagon head-to-head inside his domain, but allowing them to escape would leave him unable to cast Domain Expansion again.

Battles & Events
Shibuya Incident Arc
 * Jujutsu Sorcerers vs. Dagon
 * Toji Fushiguro vs. Dagon

Trivia

 * Dagon's appearance is most likely a reference to the works of H.P.Lovecraft.
 * Dagon's name originates from the ancient Mesopotamian and ancient Canaanite deity. A long-standing association with a Canaanite word for "fish", perhaps going back to the Iron Age, has led to an interpretation of this deity as a "fish-god".
 * Dagon is also a short story by Lovecraft about the eponymous fish god.