Complete Monster/Speed Grapher

Speed Grapher is a dark series but a number of monsters stand out.
 * Chief Ekoda is the head of the Tokyo Police Department, who hides a secret fetish: He has a thing for legs. In fact, while a member of Suitengu's Roppongi Club, Ekoda took the chance to satisfy his feitshes by kidnapping women, holding them hostage and then cutting their legs off before preserving them as trophies, molesting and killing the women himself. His first two victims were his own wife and daughter. Later in the series, Ekoda kidnaps Ginza Hibari and tries to do the same to her before she frees herself. Ekoda is set apart by being a completely human monster and his insane excesses make even the hardened Ginza reevaluate everything she had done to this point.
 * Mizunokuchi is a sadistic dentist who, as a Euphoric, is granted a multitude of spider-like limbs that he can turn into drills. In the past, Mizunokuchi operated on heroine Kagura when she was due for dental surgery, removing her lower molars while she was still conscious so he could feel her pain. In the present, the dentist takes pleasure in outright tying patients down and simply torturing them to death by drilling through their mouths. He even takes disturbing trophies of the teeth that he carves and polishes afterwards.
 * Ran Yurigaoka is an esthetician with a thing for tattoos and body art. With his Euphoric powers, he can make his tattoos come to life. Yurigaoka uses them to control other people, playing them as People Puppets for his amusement. His real joy, though, is the Giant Spider tattoo on his back. Yurigaoka uses his fame to find women and uses his powers to give them pleasure, before he paralyzes them by merging the spider with their skin. After this, he has it kill them while they're alive and conscious, but paralyzed the entire time.
 * Kamiya is a Corrupt Politician who becomes Japan's Prime Minister and schemes to take possession of the Roppongi Club, which caters to every fetish and predilection of the upper classes, away from Big Bad Anti-Villain Suitengu, while also gaining control of Kagura for his own purposes. A glutton whose power is to devour anything, before he even achieved these powers, he once drove a couple to suicide over a huge debt, and then took their children to compensate. The son he sold as a child soldier who would one day become Suitengu. The girl, who was only five, he sold as a Sex Slave to be abused and debauched until she was an Empty Shell years later, knowing only how to please men and request money for it.