Kei Munakata's (Medaka Box) Abnormality is his instinctive desire to kill. His instinctual ability as a killer is so great that he is capable of inflicting fatal injuries with his bare hands.
Akua Shuzen (Rosario + Vampire) giving her signature deranged look that is filled with killing intent.
Tyki Mikk (D.Gray-man) awakens, which instills in him a single-minded desire to kill Exorcists.
Utsuro (Gintama) has suffered persecution for centuries due to his immortality, and has developed multiple personalities that turned to serial killers and cold-blooded assassins, and the original Utsuro has became omnicidal.
Inuyasha (InuYasha), when overcome by his demon blood, has a tremendously murderous intent.
When taken over by his inner Hollow, Ichigo Kurosaki (Bleach) becomes a nigh-unstoppable killing machine.
According to Yhwach, the First Captains of the Gotei 13 (Bleach) were actually a brutal mob of killers.
Genryusai Yamamoto (Bleach) was once feared as a demon due to his ruthless leadership who even sacrificed his own subordinates and innocent lives to fufilled his goals.
Yachiru Unohana (Bleach) was feared as the most terrifying criminal of Soul Society due to her endless thirst for bloody battle which surpasses even Kenpachi.
Yhwach (Bleach) is the merciless leader of the Quincies who will readily sacrificed anyone to the point of commiting patricide by absorbing the Soul King to realize his goals.
Upon becoming a Super Saiyan 2, Gohan (Dragon Ball) became a merciless, sadistic killer who deliberately dragged out his fight with Cell to torture him.
Kid Buu (Dragon Ball) is a near-mindless killing machine who cares for nothing but wanton mass destruction. If he is not destroyed, Buu will not stop until everything in existence is wiped out.
While she has blue hair, Launch (Dragon Ball) is sweet and gentle. However whenever she sneezes, her hair turns blonde and Launch becomes a vicious psychopath.
Broly (Dragon Ball Z) is destructive, drove by Goku/Kakarot when they were infants.
Before being defeated by Naruto, Gaara (Naruto) was a near psychotic killer, especially when Shukaku influenced him.
Shukaku (Naruto) is a very bloodthirsty monster tanuki, and even more so when under the full moon.
The now extinct Kaguya Clan (Naruto) were known for their savagery and lust for bloodshed and war.
Deranged with revenge, Sasuke Uchiha (Naruto) becomes a completely amoral murderer.
When his enzymes take over, Jūgo (Naruto) becomes temporarily insane with killing intent.
When Arlong (One Piece) is angry, he enters a killing mode of sort, befitting that of a shark.
Hody Jones (One Piece) inherited the fishman's hatred for humanity since he was taught to do so, he and his crew harm their minions and the ones who are friendly to humans.
Donquixote Doflamingo (One Piece) is one of the most sadistic characters of the series. Given his childhood trauma, swearing revenge against the mob, the Celestial Dragons, shooting his father and brother, his merciless attempts to kill Smoker, Law, Luffy, and the people of Dressrosa, and turning the citizens themselves against each other.
Caesar Clown (One Piece) is a mad scientist with a bad reputation for building weapons to murder people like test subjects. He even has no problem killing his own loyal henchmen just to demonstrate the use of his inventions.
Pica (One Piece) is very sensitive about his high-pitched voice. If someone so much as snickers, Pica will violently murder them.
Due to being constantly ridiculed during his years as a slave, Gild Tesoro (One Piece) will kill anyone who dares to laugh without his permission.
Despite his flamboyant and flashy attitude, Dellinger (One Piece) becomes sadistic and bloodthirsty because of his own heritage of Fighting Fish fishman.
Gladius (One Piece) is feared for his very short temper which often gets the best of him. If someone offends him or his captain, Doflamingo in even the slightest way Gladius will use his powers to blow them up.
Caribou (One Piece) is an insane pirate known for slaughtering Marines. His sadistic nature leads to him using brutal ways to kill people such as burying them alive or suffocating them with his powers.
Cavendish (One Piece) possesses a dual personality, Hakuba, who is ruthless in slashing down everyone in range whenever Cavendish falls asleep.
"Big Mom" Charlotte Linlin (One Piece) is immensely brutal, she will ruthlessly kill anyone even her own children. What she desires above all is sweets and will destroy entire countries should they fail to give it to her.
Charlotte Brulee (One Piece) enjoyed killing attractive girls and attempted to slice Nami apart and even boil Carrot alive.
Being viciously bullied and scorned for her third eye as a child Charlotte Pudding (One Piece)…
…grew up to be very cruel and sadistic.
Amande (One Piece) is extremely sadistic, as she believes there is no meaning in slaughter without excruciating pain.
Kaido (One Piece) is a ruthless warrior who does not make himself open to negotiation or excuses. Should someone fail to comply with his demands, Kaido won't hesitate to kill them. Kaido's craving for bloodshed has given him the idea of starting the biggest war in history.
Don Krieg (One Piece) is a ruthless pirate admiral known for his underhanded tactics and mass murders. His dishonesty and brutal nature earned him the alias "Foul Play Krieg".
Jack (One Piece) has an unreasonable nature and always resorts to bloodshed. During the attack in Zou, the Mink tribe told Jack they didn't have what he sought but he chose to fight anyway, killing innocent elders and children alike during his rampage.
Rob Lucci (One Piece) is a heartless mass murderer and the strongest member in the history of CP9. At the mere age of 13, Lucci slaughtered 500 kingdom soldiers for surrendering to pirates.
Thinking of himself as God because of his Logia Devil Fruit powers, Enel (One Piece) believes he has the right to kill anyone he wants and is one of the most sadistic, egotistical, and uncaring characters of the series. He even destroyed his entire home, Birkia just because he felt like it.
The Vinsmoke Family (One Piece) are a royal family of prestigious Underworld assassins.
Akainu (One Piece) is the absolutely ruthless Fleet Admiral of the Marines, he is deeply feared by pirates and marines alike due to his complete ruthlessness.
Kuro (One Piece) showing absolutely no remorse in killing his subordinates.
A bloodthirsty psychopath, Capone "Gang" Bege (One Piece) is infamous in the Underworld for attacking mafia leaders simply for the sake of causing blood smeared chaos. His lust for bloodshed is so extreme, that he even desires to assassinate the Yonko Big Mom.
Shiliew (One Piece) is extremely bloodthirsty, he kills solely for pleasure.
Rei Ogami (Code:Breaker) ruthlessly killing evil while ignoring all pleas.
Giriko (Soul Eater) can overwhelm his opponents with sheer raw power of the blood-lust built up over 800 years.
Zahlenschwestern (Phantom of Inferno) are elite brainwashed female assassins of scythe master. They were created using the fighting data of ein,zwei and drei...
Zwei and Ein were taken by scythe master because of their natural killing instincts. They were brainwashed and trained to eliminate any threat to inferno. Zwei's eye color change when his killer instincts are activated.
Lucy (Elfen Lied) is the Diclonius meant killing humans, drove by DNA Voice.
As a creature born from evil energy, Orb (Marchen Awakens Romance) will kill anyone he wants without even a remote sense of remorse.
Influenced by the Orb, Diana (Marchen Awakens Romance) has grown into a power-hungry woman who will show no mercy to those who stand in her way of becoming the queen of MÄR Heaven.
Despite his charms, Phantom (Marchen Awakens Romance) is the mad leader of the evil Chess Pieces army, who accepted the Zombie Tattoo to become immortal. Looking down on the mortality of the world, Phantom will stop at nothing to wipe out all of humanity.
While under the influence of the Zombie Tattoo, Alviss (Marchen Awakens Romance) entered a berserk state where he wouldn't hesitate to kill his own allies.
Peta (Marchen Awakens Romance) shares Phantom’s ideals that humans are trash and feels no regret for the pain he causes others. He once even wiped out an entire fortress, not only killing enemy warriors, but innocent women and children as well.
After killing the ones who constantly bullied him as a child, Halloween (Marchen Awakens Romance) learned the pleasure of tormenting others. He grew up to join the Chess Pieces as one of their strongest and most sadistic soldiers.
After acquiring the power to get revenge on the men who tortured her, Chimera (Marchen Awakens Romance) decided to abandon her humanity as well as her original name, Eileen. From that day on, she would be known as Chimera, a monster who enjoys giving pain rather than receiving it.
Many plant manipulators, have the dream of growing a plant that reaches the sky. Weasel’s (Marchen Awakens Romance) Guardian ÄRM, Yggdrasil is a tree that grows bigger and stronger by absorbing the pain and suffering her master causes others. In order fulfill his dream, Weasel will kill and torture as many people as possible to make Yggdrasil grow.
Candice (Marchen Awakens Romance) was a sadistic army commander who showed no mercy in battle. Her bloodlust only increased when she defected to join the evil Chess Pieces.
When Rapunzel and Girom’s (Marchen Awakens Romance) father died of a disease, their mother became demented. She denied them of everything, even food and whipped them each day. This abuse would later seep into the siblings giving them sadistic personalities.
Because of his ugly face, Kouga (Marchen Awakens Romance) has been treated miserably ever since he was a boy. The abuse and humiliation drove him into madness. Ever since he joined the Chess Pieces he's had a tendency to kill those around him, especially handsome boys.
Pinocchion (Marchen Awakens Romance) is a doll brought to life with dark magic. The evil nature of the magic inside him, makes Pinocchion an insane doll who will happily kill for his own sick pleasure.
Orco (Marchen Awakens Romance) is a simpleminded but sadistic Bishop class Chess Piece. He takes pleasure in destroying buildings and along with Girom, was the one who demolished the beautiful city of Vestry.
Maira (Marchen Awakens Romance) was once nothing but a cowardly Pawn-class Chess Piece. One day however he discovered Vaqua, a Guardian ÄRM with the power to absorb others. Since then, Maira has found pleasure in using Vaqua to absorb as many people as possible.
Maruss (Zatch Bell!) is a short tempered mamodo who finds pleasure in taking his anger out on innocent people. Due to Tia getting away from him so many times, he threatened that once he burned her book he would attack her bookkeeper's concert.
Zofis (Zatch Bell!) is a heartless mamodo who only cares about becoming king. After brainwashing the sweet Koko into becoming his bookkeeper, Zofis forced her to burn down her village.
Koko (Zatch Bell!) became sadistic because of Zofis' mind control and enjoys hurting people just as much as her mamodo does.
Clear Note (Zatch Bell!) believes killing mamodo is the very reason for his birth and only wants to become king so he can bring genocide upon his people.
Despite being an infant, Clear Note's bookkeeper, Vino (Zatch Bell!) enjoys helping his mamodo and gets sadistic pleasure in hurting people and mamodo alike.
Driven insane by her hatred for King Solomon ,Arba became immensely sadistic and brutal willingly to kill even her own descendants for both world annhilation and sadistic entertainment.
Due to his father corrupt teachings, Felix Aaron Thenardier (Madan no Ou to Vanadis)...
grew up to become an extremely ruthless and brutal tyrant.
Esdeath (Akame ga Kill) is terrifying and murderous sadist who enjoyed most brutal battles and ending people's lives in the most agonizing ways.
Goblin Slayer (Goblin Slayer) is completely ruthless in hunting down goblins, to the point of massacring any goblins nest he can find including children.
Charlotte Katakuri (One Piece) is fiercely loyal to his mother Linlin and is willing to ruthlessly kill to realize her goals.