Unsubs in each group are listed by first appearance.
- Carl Buford is a pillar of the community in Cabrini-Green, where Derek Morgan grew up. Running a youth center, Buford is in truth a pedophile who grooms young boys by doing them favors to slowly build up their trust before giving them alcohol to lower their inhibitions and raping them, which was the fate of Derek Morgan himself as a young man. One victim is so traumatized that he later projects Carl onto other men later in life and brutally murders them while repeating the phrase Carl used for the boys while raping them. Carl has also murdered three boys to keep his secret, and when sentenced, he takes the name Mohammed Alam while joining a Muslim gang. When Morgan goes to see him for information, Carl takes a special delight in toying with him, mocking him over how "special" Derek was to him, while revealing he has molested at least 57 boys, even blaming Derek, telling him "you could have said no". Even his gang are revolted upon learning the truth of Buford's crimes, and he remains one of the most chillingly realistic depictions of a predatory sex offender on Criminal Minds.
- The Boston Reaper, George Foyet, returns after retiring from a killing spree for which he was never caught, following the death of the original investigator. Killing again, the Reaper calls investigator Aaron "Hotch" Hotchner, agreeing to stop his killings with the addendum Hotch abandon the Reaper's case. His deal rejected, the Reaper massacres a bus full of people and kidnaps and threatens a journalist before being arrested by Hotch. Boasting that he kills for fame, the Reaper escapes from prison, stalking Hotch to his house and torturing him into a coma. Dropping Hotch off at a hospital, the Reaper leaves notes indicating he intends to target Hotch's ex-wife, Hayley and young son, Jake, next, mutilating then killing the officer assigned to protect them. Murdering Hayley, the Reaper calls Hotch to torment the powerless man over the phone as he closes in to kill Jake.
- "To Hell...And Back": Mason Turner proves to be among the nastiest unsubs the BAU has faced. Unable to hunt and kill his victims himself due to being paralyzed from the neck down, the sadistic and arrogant Mason manipulated his mentally handicapped brother Lucas into becoming a killing machine. Mason has Lucas drive to Detroit to kidnap transients and haul them back to their pig farm in Canada, where Lucas brutally slaughters them by crushing their neck with a sledgehammer. Mason then guides Lucas through performing pointless, cruel experiments on their remains before discarding them by feeding them to the pigs. Through this process—which Lucas watches through a complex series of mirrors to satisfy his sadistic tendencies—Mason has claimed 89 lives, and is only stopped from killing a 90 victim when the BAU raids his farm. Mason tries to pin his crimes on Lucas, who he encourages the BAU to shoot on sight. Once he's exposed for the monster that he is, Mason is smug and completely unapologetic about his crimes, coldly stating that his victims were worthless trash.
- Season 10: Alex Zorgen runs a Human Trafficking ring that has sold dozens of victims, mostly women, regardless of age, to serial killers and other criminals online, with said criminals killing them. In 1993, prior to creating this ring, he abducted a woman named Donna Mangold, repeatedly raping and torturing her for the next 22 years, with one of those rapes resulting in a son named Kyle. As the season progresses, Alex has Kyle stalk the BAU's newest member, Kate Callahan, by posing as an attractive high school senior online to gain their trust of her niece Meg, and her friend, who are both 14 years old. He sends Kyle and Donna and Kyle to kidnap them, but Kyle only catches Meg, which results in Alex killing Kyle without any remorse, before selling Meg. When the BAU later arrests him and ask him where Meg's captor is keeping her, he refuses to cooperate and just taunts Kate about the things her captor is going to do to her.
- "Believer" & "300": "The Messiah", Benjamin David Merva, born David James Merva, is possibly the most prolific serial killer ever faced by the BAU. Merva, aka "the Strangler", a survivor of the Liberty Ranch hostage crisis, eventually founded the Believers. The Believers kidnap people from all over the country—protector types according to the BAU—and Merva kills them, giving the hyoid bones to the Believers. Just as 300 angels protected the Garden of Eden, Merva aims to collect 300 hyoid bones. He has killed 299 people so far, and plans to make Spencer Reid the 300th victim.
- "The Tribe": Jackson "Grandfather" Cally is a chilling combination of extreme sociopathy, charisma, and bigotry. A cult leader native to Terra Mesa, a mostly-white New Mexico town known for tensions with a mostly-Apache town nearby, Cally preys on troubled teenagers interested in Native Americans, indoctrinating them into being willing to kill for him under the pretense of "helping" the Apache reclaim all their ancestral land; while keeping his true goal, attempting to foment a race war that would wipe the Apache out, a secret. He first sends his cult to a college dormitory built on former Apache land, having them massacre the residents in gruesome ways such as sknning them alive and impalement, mimicking Native American war rituals, in hopes the Apache would be blamed and the whites would retaliate. When the FBI rule out the Apache as suspects, Cally has his men, after killing the police officer watching the house, kill the leader of a local racist group, his wife, and his three daughters. His final and most wicked gambit, however, is to dress up his men as members of the racist group and send them on a wholesale massacre of the Apache town's school. When foiled and caught by the FBI, Cally's only justification for his actions is that he hoped to show the world what "savage animal(s)" the Apache people "really" are.
- "Legacy": Charles Holcombe, a callous serial killer with over 60 victims to his name, is dedicated to wiping out the homeless, junkies, prostitutes, and vagrants, viewing them as subhuman filth who are worthless to society. Using a meatpacking plant he inherited from his late father, Holcombe re-outfitted it into a brutal maze-like Death Course where he forces his victims to play a sadistic game, where they must escape before sunrise or die horribly. What follows is his victims being put through horrible physical agony, including broken glass, gas, and a Doberman. The whole time, Holcombe torments his victims with footage of him dissecting his previous victims alive to let them know what to expect if they fail. When his latest victim, a prostitute named Maggie, successfully completes the course, Holcombe reveals that he had no intention of ever letting her escape and knocks her out with a spray of gas before hauling her off to slaughter. Ruthlessly obsessed with his mission to the end, Holcombe's final moments before being gunned down are him attempting to finish off Maggie while screaming "Let me do my job!"
- "Mosley Lane": Anita Roycewood is a serial kidnapper and child murderer, who forces her submissive husband, Roger, and first kidnap victim, Charlie Hillridge, to help her abduct and imprison children. Keeping the children locked up in a hidden hallway, Anita renames them, dyes their hair, and is implied to sexually abuse them, using fear, beatings, and threats to the other children to keep them in line. When the children grow too old for her liking, or become uncontrollable, Anita knocks them out, in the case of Stephen Shepherd beating him savagely beforehand, places them in a cardboard box, and burns them alive in a crematorium, whistling jauntily the entire time. When the police catch onto her, Anita abandons Roger, and takes the three remaining children, Aimee Lynch, Mae Hall, and Charlie, to the crematorium, where she tries to force Charlie to help her burn the other two; she then intends to kill him. Guilty of some of the most callous crimes yet shown on the show, and viewing her victims as replaceable, Anita's reasons for doing what she does are never explored, leaving only an utterly hateful cipher for the cast and the audience to deal with.
- "A Rite of Passage": Deputy Ronald Boyd kills undocumented immigrants because it allows him to assert a sense of power that he otherwise lacks, with over 40 victims to his name. When the Hispanic sheriff, whom Boyd loathes for being new to town, starts looking into the missing persons, Boyd sends her progressively more aggressive "messages"—severed heads in boxes outside the sheriff's office; a severed head on a pole in her front yard—until he finally kills her for sticking her nose into his business, while ranting that his victims aren't missing because "they ain't supposed to be here in the first damn place". Dismembering her corpse to pin the blame on drug kingpin Omar Morales, Boyd proceeds to murder Morales and most of his gang to cover his tracks; also because they're Hispanic. When his partner objects, Boyd shoots him and places the gun in the hands of the dead Morales.
- "Remembrance of Things Past": Lee Mullens, aka "The Butcher", is a sadistic serial killer who murdered 24 women. Mullens would kidnap these women to torture and sodomize with electrical equipment and sharp objects; he would stab his victims in non-fatal areas to maximize their pain while making them call their loved ones and force them to say that "they enjoy it". He would also manipulate his son, Colby Bachner, into knocking out his mother and making him watch as he kills her. This led to a vicious cycle of abuse on Mullens's part eventually turning Colby into an unwilling accomplice of Mullens's murders, kidnapping 3 women for Mullens to torture and kill.
- "Into the Woods": Shane Wyland is a prolific killer and rapist of boys. Put on parole after the sexual assault of a ten-year-old boy in Harrisburg, Pennsylvania, Shane abandoned civilization in favor of the woods along the Appalachian Trail to make it easier for him to hunt children. After selecting a child, Shane would stalk them before abducting them and imprisoning them in an Abandoned Mine, where he would repeatedly molest them throughout the winter before finally killing them. Shane kidnaps a young boy named Robert, as well as his sister Ana, who Shane intends to kill. While holding them captive within a storage cell, Shane molests Robert. After Ana flees captivity, Shane takes Robert to the hotel of a fellow pedophile, Brandon Stiles, where he offers to allow Stiles an hour alone with Robert in exchange for painkillers to treat his leg injury.
- "Supply and Demand": "Lucy" is the psychologically sadistic head of a Human Trafficking ring. She and her gang target stressed-out college students, with Lucy herself scouting the victims. She and her gang then kidnap the young men and women and pimp them out to various sexual deviants, staging live shows in which the victims are raped, tortured, and even killed, by her men and/or clients. At least once, she pretended to be a victim, gaining the trust of undercover agent Renee Matlin, before revealing herself as the leader of the ring. When Lucy discovers that Matlin is an undercover cop, Lucy proceeds to play a game of Russian Roulette with her, then has her savagely beaten, gloating the whole time. Interrupted by the police, Lucy manipulates Max, one of her associates, into being killed by them, planning to frame him for her crimes. She then pretends to be a victim, and when found out, tries to shoot Rossi, but is fatally shot by Morgan first.
- "Proof": Ben "Cy" Bradstone is a mentally handicapped man who uses Obfuscating Stupidity to lure women out of the public eye and into his shed where he rapes them and then stabs them to death, with said shed containing tapes showing countless more victims. He first stabbed their eyes out, but later evolved to using sulfuric acid to burn away their senses, choosing the sense depending on how they react to him. He targets women who remind him of his sister-in-law, whom he attempted to molest when they were both teenagers. When his niece puts on the same homecoming dress her mother—said sister-in-law—wore, Cy kidnaps her and burns her hands. After his arrest, his brother Matt, demanding to know why Cy did this, who tells him that he has always hated Matt and was planning to deafen and then kill him one day.
- "A Thousand Suns": Hayman Vasher is an aerospace engineer who is a big admirer of Robert Oppenheimer, especially how he progressed from socially-awkward to world-renowned. For Vasher, who after being humiliated on a date dropped out of society, this involved building a device which can hack into airplanes and control them. As a "test", analogous to the Manhattan Project's Trinity test, Vasher makes a plane crash in a sparsely populated area, resulting in over 150 deaths, including the woman who he had dated. As his Hiroshima, Vasher takes control of a plane with over 300 people and plans to crash it into a populated area. He agrees to let the plane land if the BAU calls off fighter jets which have scrambled to shoot the plane down if necessary, but once this happens, Vasher tries to crash the plane anyway, before he and his device are both shot. Vasher was also looking at other flights, meaning that there might have been still other crashes had he not been stopped. Driven only by his need for attention and enjoying "playing God or some other deity", Hayman Vasher, profiled as "a mass annihilator who wants to eradicate life on a large scale", is one of only a few unsubs to successfully have a triple-digit body count.
- "The Witness": Mitchell Crossford is the son of an anti-government cult leader and later adopted this extreme ideology. When his half-brother Theo, with whom he was planning to launch terrorist attacks, started having an affair with a married woman, Crossford, enraged, plotted revenge. He acquired sarin gas from a disgraced chemist—who Mitchell then killed—and placed sarin on a bus the woman usually rode; she wasn't on the bus that day, but 10 other people were killed. While stalking his brother, Crossford saw Charlie, the woman's husband, murder Theo, and manipulated him into becoming his patsy, threatening to report the murder, while also threatening Charlie's 12-year-old daughter. While he may have planned even more attacks, his main goal was using Charlie to launch a larger sarin attack on the FBI building in Los Angeles. Over a thousand people were at risk, before the FBI successfully evacuated the building and sealed the garage where the sarin was placed.
2017 Korean Series
- Kim Yong-chul, aka the Reaper, is a black-hearted, self-proclaimed "devil" of a man seeking to inflict pain to all around him and cement himself in infamy. A serial killer who took a hiatus after 21 victims, including his own girlfriend, Yong-chul returns to continue his slaughter in the present, focusing on NCI leader Kang Ki-hyung as his Arch-Enemy. Killing several more men, women, and children, Yong-chul then murders Kang's wife and attempts the same to his child, before beginning to target friends and family of the entire NCI team. In his grandest scheme, Yong-chul traps 5 young teenagers in a room seemingly filling with gas, leaving a single oxygen mask in the hopes they will rip each other apart for it, and then murders the commissioner after failing to force him to murder an innocent woman in exchange for his daughter. The Reaper dies mocking Kang about his dead wife, and cements himself as the worst and most personal foe the NCI team ever faced.
- Episode 5: Choi Ho-sung is a former military officer known for abusing subordinates who returns from war intent on spreading an anthrax virus across the country. Experimenting on and killing 3 innocent men with the virus, Ho-sung murders his partner for trying to stop the killing, and then unleashes the virus in a park to infect 72 people, leading to many of their deaths. Ho-sung's grand plan is to flood Independence Hall with the virus and kill hundreds of people, including an entire school group, and when this is foiled, attempts to detonate a bomb filled with the virus in the middle of a city square, cackling with glee as he prepares to kill hundreds, if not thousands, of innocent people in the name of "spreading chaos".
- Episode 12: Jo Young-hoon is a psychopathic murderer of over a dozen young women via torturing them to death with power tools and dismembering their bodies. Having forced them to dress as children and pose for pictures for him to keep as trophies, Young-hoon giddily drags out the suffering of his victims' families while bragging of his plans to go down in history as one of the worst killers in the country's history. Before capture, Young-hoon ordered his innocent wife to kill their child son, and then promptly framed her as his willing partner, simply to get her killed as well. Young-hoon dies while smugly revealing he has a half-dozen more victims than had been found, taking sick enjoyment from the idea that more people will suffer because of him.
- Episode 14: Kim Jung-soo is a pedophilic youth center worker, who sexually assaulted at least 6 young children at the center, keeping many of them under his thumb for years and continuing his abuse. When a young girl witnesses his crimes and tries to expose him, Jung-soo beats and strangles her to death, then bribes and blackmails a police detective into murdering two of Jung-soo's young victims to silence them. When confronted about his crimes, Jung-soo cowardly tries to shift blame to anyone but himself and pleads for a mercy he never showed any of his victims.
- Episode 18: Kim Young-soon is one of the only serial rapists the NCI team encounters, and easily the worst. Flying into a rage after his girlfriend, who he regularly abused and raped, left him, Young-soon brutally beat and raped several college girls, leading to one of them committing suicide. Continuing to rape and beat several more women, assaulting their boyfriends and even forcing a child to watch one of the rapes, Young-soon then kidnaps NCI member Ha Sun-woo and tries to rape her as well. Young-soon reveals that he chose all of his targets in an attempt to impregnate them so as to create more people like himself, who "see" women for the whores and degenerates they are.