Jagi is by far the most heartless of all of Kenshiro's villains. At first he was a stupid loudmouth punk who fought dirty and occasionally had to shoot a guy to make a point. Murdering an innocent child by chaining a cinderblock to his leg and leaving him in the middle of the desert to die was what pushed him over the Moral Event Horizon. With a nuclear-powered bulldozer. He also murdered Rei's family, kidnapped Rei's sister Airi on her wedding day, and sold her into sex-slavery with the Fang Clan. He then manipulated Kenshiro's best friend, Shin, into kidnapping Yuria due to his jealousy and unrequited love, which led to the mind-scarring event of Kenshiro seeing Yuria taken away from him, being betrayed by his best friend, and getting his seven scars. Just like Kenshiro said, hell is too good for him.
There's Amiba, a Mad Scientist with Hokuto Shinken who conducts horrible experiments (based on Unit 731) on peoples' pressure points, often making them explode quite gorily. He doesn't even show remorse when conducting these experiments on children and impersonating a good man like Toki to destroy his name. Why? Because Toki slapped him once, and not even deliberately at that — he rushed past Amiba, and his hand brushed Amiba's face without Toki noticing.
Emperor Souther is an example of a villain whose Freudian Excuse doesn't even BEGIN to overwrite his atrocities or explain anything. Souther runs a brutal empire that enslaves thousands of innocent children and works them to death. He poisons supplies he knows the rebellion will steal and throws himself huge banquets, eats a small plate, and destroys the rest, all for the sick glee of watching the starving slaves suffer. His old friend Shu, the rebellion's leader? Souther forces him, with cut tendons, to make his way up an enormous pyramid holding the enormous stone cap piece meant to finish it...if he drops it, every single slave will die; and if anyone helps him, Souther tells them their families will be executed. And then, once Shu finally does make it to the top of that pyramid? The bastard orders his archers to put arrows into him, and then finishes him off with a thrown spear. To say that Kenshiro was utterlypissed at this is quite the understatement. And the Freudian Excuse in question? Because he was forced to kill his beloved master to master the Nanto Ho'ou Ken. The amount of grief he experienced was so much that he swore to never love and became as much as a bastard as he can. Gee, you'd think he'd try to man up rather than just run off from challenges of the grief coming with love like that.
Abida, one of Raoh's former subordinates, had his soldiers play cruel games on the villagers (since Raoh was gone) who he would hand-pick between big gulps of alcohol. Namely, him and his child-like underling Gonzu would chain giant rings on the villagers' waists and swing them as far as they could to see who could throw them the farthest.
Jackal, a biker based off Toecutter from "Mad Max." Jackal takes over an orphanage village for its supplies, yet even after the orphans and their caretaker are subdued, Jackal feels the need to sadistically kill them. Jackal purposefully gives the old lady a mortal stab wound, just so she could live long enough to watch one of the orphans hanged by his men. Later, Jackal manipulates a giant convict to become his pawn to fight Kenshiro.
Hiruka, a minion of Raoh. His crimes include: Having his men whip captured orphans, throwing his own two biological sons into an agonizing death in quicksand just to get Fudoh. It's made clear he enjoys all of this.
Targel, an underling of Uighur, is distinctive in that despite being a filler character and therefore only showing up for one episode, manages to cruelly murder three innocent people during his brief screentime. Specifically, a martial artist (in front of his wife no less), and a Cassandra prisoner known as Bella (along with her elderly mother).