Complete Monster/Rurouni Kenshin

In Rurouni Kenshin, there are these extra despicable individuals.

Anime and Manga

 * Psycho for Hire Jin-e Udo is a remorseless Blood Knight and Serial Killer who lives for killing. In the era of peace, Jin-E makes his living as an assassin who goes out of his way to slaughter as many human beings as possible for the fun involved. when he encounters Kenshin Himura again, Jin-E becomes obsessed with turning Kenshin into a killer like him and kidnaps his love interest Kaoru Kamiya. When Kenshin arrives, Jin-E uses his powers of hypnosis to freeze her in place and force Kenshin to break his vow to never take another life as the hypnosis will be lifted only if Jin-E dies and Kaoru's body will shut down within minutes.
 * Drug-dealing scumbag crimelord Kanryu Takeda: corrupt drug dealer and tycoon who murders Megumi's ex-boss, then forces her to prepare a highly lethal brand of opium via killing her boss and enslaving her, then breaks her further via a Sadistic Choice, and ultimately kills Aoshi's Oniwabanshu subordinates with a gatling gun, pushing him towards the Despair Event Horizon.
 * Gein, Enishi's Dragon. He's a Psycho for Hire, Blood Knight, and an all around sicko who joins Enishi's campaign and offers him advice on Mind Rape-ing Kenshin, not for revenge, but for kicks and a chance to test his abilities. He makes puppets out of corpses, kills or murders pretty much everyone who crosses his path, works as an arms dealer, sees war as a chance for fun and intellectual masturbation, and was the mastermind behind the plan to fake Kaoru's murder, just to screw with Kenshin's head. On top of that, he was named after Ed Gein.

Live Action Film

 * Kanryu Takeda likes to pass himself off as a successful businessman and an example of what the Japanese can accomplish in the new era of the Meiji. However, below that he is a oppressive drug lord who takes glee in finding, then murdering, police informants and putting them in the open so people could find. He also directly murders through Jin-E a department of the police while chasing after Megumi Takani who he had forced to make his brand new opium. To test the new opium as well he kidnapped users off the street, locked them in his secret room in his office, and saw how far they degraded while under his new drug. All with a smile on his face. However his worst act is when he learns Megumi is taking shelter in the Kamiya Dojo and after Kenshin refused to be bought by him: he poisons a district all around the Kamiya Dojo. If it wasn't for Megumi, there'd be hundreds, if not thousands of deaths directly on his hands.
 * Jin-E Udo seems like a normal Psycho for Hire, but he doesn't murder and kill for profit. He just likes to kill. When he pulled himself out of the mountain of corpses he accumulated in the Battle of Toba Fushimi, he took up Kenshin's killing sword as his own. And for ten years, he's committed murders in Kenshin's name-calling himself Hitokiri Battosai to strike fear into people. When he storms the police department on the trail of Megumi Takani, he could have easily just evaded the officers. He didn't, he went and purposely started a horrific attack on the station and left a gory tapestry of death, even messing with one officer with his 'Shino Ippo' to force him to stand still as Jin-E impaled him slowly to savor it. In the last act of the film he kidnapped Kaoru while Kenshin was saving Megumi from Kanryu. When Kenshin showed up, he first kicked Kaoru down a stone staircase to make sure she'd hit every step just to piss Kenshin off, and then using the Shino Ippo he paralyzed her lungs. Again, just to piss Kenshin off. And when Kaoru broke through it with her own spirit and after Kenshin had shattered his elbow, Jin-E still attempts to have the last laugh by stabbing himself just to spite Kenshin and spit on his Thou Shall Not Kill code.