Orochi

"I don't know where you crawled in here from, but you are clearly not just some human trash that can be ignored."
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- Orochi to Saitama

"As you wish, I will bestow upon you terror."
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- Orochi to Garou

"Looks like this will be the final showdown between the strongest. You sir have truly piqued my interest... A human who is able to reach the pinnacle strength of living organisms. How effective that will be against me, I'm somewhat looking forward to it"
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- Orochi prior to his introduction to Saitama

Summary
"Monster King" Orochi ("怪人王"オロチ, Kaijin-ō Orochi), also called Lord Orochi (オロチ様, Orochi-sama), is a Dragon-level Monster and the leader of the Monster Association.

Orochi is one of the main antagonists of the Human Monster Saga.

Formerly a human, he was a fighting genius who turned his back on humanity and was transformed into a monster by Gyoro Gyoro.

Powers and Stats
Tier: At least High 6-C, likely Low 6-B

Name: Orochi, Monster KIng

Gender: Male

Age: Unknown.

Classification: Monster, Leader of Monster Associatin

Threat level: Above Dragon

Attack Potency: At least Large Island level, likely Small Country level+(Murata implied that he is comparable to Golden Sperm. Stated to be far superior to Gouketsu.)

Speed: At least Sub Relativistic (Easily blitzed Half-Monster Garou. Caught Awakened Cockroach before he could react whose speed was compared to Sonic by Genos.)

Lifting Strength: At least Class G (Stated to be far superior to Gouketsu.)

Striking Strength: At least Large Island Class, likely Small Country Class

Durability: At least Large Island level likely Small Country level+

Stamina: Very high (Should be superior to Gouketsu.)

Range: Tens of meters, Kilometers with energy attacks (His energy attacks can go even farther than Gouketsu's shockwaves which reach clouds.)

Intelligence: Gifted (As a human, Orochi was a fighting genius and he remains a martial arts prodigy capable of easily defeating masters of martial arts and replicating their techniques and styles after only seeing them once.)

Weaknesses: None notable.

Notable Attacks/Techniques:

Metamorphosis: Orochi's main and most terrifying ability is to change the shape of his body at will. He can shift to and from his humanoid and more monstrous appearances, revealing his "released form" while unraveling his bipedal appearance into a nest of monstrous dragon-like protrusions all along his body. There are nested mouths in place of his face and head while his limbs transformed into dragon-headed coils with their own appendages and extremities. When he wants to fight with his full capabilities, Orochi shifts from his released form to a humanoid final form more suited for battle. After his body is nearly destroyed by Saitama, he is still able to manipulate and transform the bits of his flesh around the headquarters
 * Elasticity: Orochi is able to stretch and deform his physical shape like taffy whether in his concealed or natural forms. He can stretch his arms a good distance away, and snap it back like a rubber band afterward.
 * Shapeshifting: On top of transforming his limbs into dragon-like worms, Orochi can make his coils sheathe and project tooth-like protrusions to act as his fingernails, indicating that he has some form of transformation capacity beyond just mode shifting. He has gotten larger from his initial monster form back when he first became a monster, suggesting some control over his size.
 * Tendril Generation: Orochi can unravel his body into a nest of dragon-headed tendrils with their own faces, claws, and fangs that they can use to bite and scratch. After learning an enemy's fighting style, he can also use their skills in conjunction with his serpentine limbs.
 * Horn Manipulation: Orochi can extend his horns over long distances. They are incredibly heavy yet able to change and alternate their trajectory very quickly. Bofoi's drone was destroyed by a single strike from his horn.

Monster Cell Generation: While the process has never been shown, Orochi is able to generate Monster Cells with his body. The Monster Cells are harvested from Orochi and then nurtured using a large machine in the Monster Association base. Because he is the source of the cells, he can create as many Monsters as he wants.

Fire Manipulation: Orochi can breathe fire from his mouth and from all of the dragons over his body. The intensity of his flames prompted Gyoro-Gyoro to create a barrier to protect herself, and the flames are ejected from his dragons' mouths so quickly that they appear like beams of glowing energy. The fire is powerful enough to melt and explode the stone environment surrounding him. Had Gyoro Gyoro not protected herself, the fire would have burned her to death. When he transformed during his fight with Saitama, his dragons also changed shape and became completely enveloped in flames.

Electricity Manipulation: In his final form, Orochi can also generate electricity, allowing him to fire a massive blast of lightning that spread across the headquarters of the Monster Association.

Energy Projection: During his fight with Saitama, he is revealed to have the ability to project large blasts of energy. His dragons also shoot beams of energy. He is also capable of using his dragons to unify the energy blasts into a single energy beam. His energy blasts are strong enough to shake the entire area, destroying many buildings and raising the terrain several hundred meters into the air, while creating a massive tunnel. His energy beams are also strong enough to slightly penetrate through Tatsumaki's defenses, slightly tearing and singeing her dress.

Absorption: Orochi's body can absorb other organisms that touch him as well as lash out with tentacles to grab at other creatures and pull them into his mass. Endless Growth: Orochi's voracious appetite contributes to his progression cycle. By eating other mysterious beings the Monster King gains both in size and power according to Gyoro Gyoro.
 * Regeneration: Using the blood of absorbed creatures, he can regenerate his body from the brink of death. However, he is only shown to be able to regenerate starting from his heart.
 * Esper-Fusion: If Orochi absorbs an esper of sufficient power, the esper can suppress Orochi's control and take over their fused body, although Orochi still retains a degree of control due to his immense power. This then tremendously amplifies the esper's abilities

Genius Combatant: Similarly to Garou, Orochi can instantly learn any move used by his opponents. With just one look, Orochi mastered Water Stream Rock Smashing Fist to the same level as Garou.
 * Water Stream Rock Smashing Fist (流水岩砕拳, Ryūsui Gansai-ken): A martial art Orochi copied from Garou. He uses Water Stream Rock Smashing Fist with his horns and his multiple dragons tendrils as arms against Garou. He is seen using this fighting style against Saitama.
 * Gouketsu's techniques: While never explicitly displayed as such, Orochi defeated Gouketsu in one-on-one combat prior to the series and took some of his moves for his own.