Hurray! The heroes have captured the murderer and locked him away, and the day is saved.
So why is he getting all this fan mail?
The Monster Fangirl (and this is almost Always Female, though the genders may be flipped) might have the belief that Love Redeems, or she's In Love with Your Carnage (in the worst case), or believes that he's really innocent. If she's aware of his evil nature, it's essentially a form of All Girls Want Bad Boys turned Up to Eleven.
Their fate is usually to be casually discarded to wind up another victim, or to go to jail for the crimes they commit to aid the Monster, often screaming declarations of love all the way. As a villain is not always redeemed, the woman's deluded attraction to the dangerous psychopath may also be a romantic manifestation of Too Dumb to Live.
Compare Draco in Leather Pants for when the fandom does it. See also Psycho Supporter, Nightmare Fetishist and Horrible Judge of Character. For a fangirl of a literal monster in a relationship with one, see Interspecies Romance, Beast and Beauty or You Sexy Beast.
- Death Note:
- Light Yagami founds over half his schemes on these people. Misa Amane had some potential as a less-polished monster in her own right, as a less brilliant and histrionic psychopath instead of a genius narcissistic one, but decided to slave her entire being to his will on first meeting, and never wavered, and without that his plan to defeat L would never have begun to exist. His final big scheme also relies heavily on Disposable Woman Kiyomi Takada, a college girlfriend turned news anchor whose response to the revelation that he is Kira is not visceral horror but infatuation.
- The rest of the Kira fans who keep him in names and faces to kill (yay fact-checking!) and cheer and all, and also his eventual right arm Teru Mikami, are a bigenderal hydra of this phenomenon stretching across the world. Even after the Villain with Good Publicity is exposed and declawed and killed, he still has a huge cult. This series is founded upon existential despair.
- From Death of the Family, Harley Quinn once again. The sad thing about this is that it looked like she had moved on from the Joker.
- This has been touched on before, especially in the comic (and episode based on it) "Mad Love". After being tossed out of a 3-story window for daring to (and worse, succeeding) capture Batman without him and breaking so many bones, Harley decides to give up on the Joker. And then she sees the rose and apology letter he gives her...
- Judge Dredd: The lead-up to the "Necropolis" arc had a rather tragic justified example. After a woman barely survives an encounter with Judge Death, a psychopathic Omnicidal Maniac from another dimension, it creates a psychic link between the two. She basically becomes a smitten fangirl of Death and dreams about becoming his bride. She then helps his allies Phobia and Nausea to cross the dimensional span into Mega City One by sacrificing her husband, for which Death rewards her by ripping out her heart.
- In one of his limited series, Venom gains a crowd of child admirers on Halloween (one wearing a Spider-Man costume, ironically) after saving one from a mugger - the fact that he brutally killed the mugger is lost on them. He might have even given one an autograph if the police weren't coming.
- In the first part of the Maximum Carnage storyline, Carnage was in the middle of his latest rampage within the maximum security facility he had been sent to, when to his disbelief, he gained a cheering section. Of course, the fan in this case was fellow inmate Shriek, who was almost as sociopathic as he was, but they would become partners as a result.
- Male examples: in The Simpsons fanfiction The Yellow Mile, a grown-up Maggie, who is on death row after killing one of the gangsters who murdered her parents, briefly contemplates the number of marriage proposals she's been getting.
- Sabrina in Pokémon Reset Bloodlines is revealed to have been this as a child. At one point, she wrote a school essay about a person she admired. Her chosen subject was Twenty Gyarados Bill, a notorious criminal whose titular Gyarados devastated the coast of Johto and the reason why the six active Pokémon limit was established. While she doesn't deny he's a mass murderer, she tries to highlight his more positive traits, describing him as "a shinning example of self-improvement through hard work and determination".
- In the opening of Men in Black 3, Boris the Animal escapes from his Lunar Prison when his prison mail girlfriend brings him a cake containing his lethal symbiont. The kill-crazy alien monster thanks her for her aid to him, but lets her be sucked out into space without remorse and goes back to trying to destroy Earth.
- Downplayed at the end of The Pink Panther (1963) when Clouseau is framed as being the jewel thief The Phantom. He's hauled away to jail but there are legions of screaming fangirls outside.
- The Petrified Forest: A very rare male example in the person of Grandpa Maple, an old coot who hangs out at his family's gas station in the Arizona desert. He loves to tell the story of how Billy the Kid once took a shot at him, and he is only too thrilled when Duke Mantee the notorious gangster arrives and takes them all hostage.
"It certainly does feel great to have a real killer around here again."
- Sissi from the Nightfall Series has become obsessed with Prince Vladimir, the Big Bad who has destroyed the world and is breeding the surviving humans for vampire food. She's drawing pictures of him and is writing stories about him. She ends up at the Resistance because she's gone on a probably deadly journey to meet him.
- The Harry Potter franchise has Bellatrix Lestrange, tenaciously devoted fangirl to Voldemort, and according to J.K. Rowling, is obsessed with Voldemort despite his complete inability to feel love, compassion or even pity for another being.
- The "fiance" of Nate Haskell in the CSI episode "Targets of Obsession". He has a whole club of Monster Fangirls.
- Baltar's cult in Battlestar Galactica sheltered Baltar after his trial from the many, many people who wanted him dead.
- In Bones, Serial Killer Howard Epps got married to one of these while in prison. Then he escaped and killed her.
- Several episodes of Criminal Minds, with "Riding the Lightning" and "The Angel Maker" being the most prominent examples.
- In "Riding the Lightning", the Serial Killer has a horde of fangirls who call themselves "The Brides of Jacob" and deliberately dress up as his victims.
- In "Devil's Backbone", Psycho Therapist Antonia Slade has either several Monster Fanboys including the unsub or just the unsub using several aliases.
- Gender Flipped in Criminal Minds: Suspect Behavior with Veronica Day's Monster Fanboys.
- In Flashpoint, "Jamie Dee" takes a hostage to steal a policecar. It turns out the "hostage" is one of his fangirls. However, he's not what he seems.
- Dexter himself gets a fangirl in Lila, who sees him as a misunderstood creature and her soulmate when she finds out that he is actually a prolific Serial Killer. She turns out to be dangerously insane herself, and he eventually kills her after she tries to kill his girlfriend and her children.
- The killer in Season 6 gets legions of online fans, plus a pair of fans who actually aid him in a kill.
- Red John from The Mentalist seems able to recruit fanatical followers of both sexes.
- One of the criminals in Lie to Me (a rapist who blinded his victims) had a Monster Fanboy who was so devoted that he married one of the victims so he could be "close" to what had been done to her.
- Law & Order: Special Victims Unit had an artist who has almost a dozen followers who commit murders, as he encourages them to be creative and to impress him. In the end he gets sent to a Super Max prison where he will have no contact with anyone in the outside.
- William Lewis escapes from prison with the help of a pair of these, one of whom is a doctor, thus showing that this is not strictly a low-IQ trait.
- On Unbreakable Kimmy Schmidt, the Reverend who held Kimmy hostage for 15 years has a fiancee despite being in prison. Kimmy finds this out when he calls her asking for a divorce (since apparently he legally married her while she was a hostage) and a whole episode revolves around her and Titus trying to convince the woman not to marry him. Turns out the woman is marrying him because of her horrifically low self-esteem; in her words, she's okay with marrying a prisoner because he'll never spend enough time with her to find out how terrible she is.
- In The Beatles' "Maxwell's Silver Hammer":
Rose and Valerie, screaming from the gallery
Say he must go free
(Maxwell must go free!)
- Frank Zappa: "The Illinois Enema Bandit", about a real life criminal who gave his female victims enemas. When sent to court "one girl shouts: "Let the bandit be" and another one shouts: "Let the fiend go free."
- In the Batman franchise Harley Quinn is one to the Joker. More specifically she was his therapist until she suffered a Critical Psychoanalysis Failure.
- Inque in Batman Beyond had a male version. He helped her escape and tried to become like her. She pays him back for his help by giving him a half-way working solution. He becomes something like her, all right.what happened?
- The Simpsons: In "Pranksta Rap", Kirk Van Houten is arrested for kidnapping Bart. Even though he is innocent (as Bart staged a fake kidnapping), Kirk is happy to be in jail because he has a cleaner home, three meals a day and single women cheering for him.
- Villainous has Demencia, a Loony Fan of Black Hat who keeps breaking into his lair and trying to help with his product demonstrations.
- In medicine, this is sometimes called hybristophilia, a paraphilia in which one is sexually aroused by the fact that somebody has committed a heinous crime. Some famous examples include:
- Marriage proposals to inmates, and serial killer groupies. Quite famously, the "Night Stalker" Richard Ramirez wound up actually marrying one of his admirers. Scott Peterson, a man convicted of murdering his pregnant wife in a highly-publicized trial, received his first proposal from someone wanting to be the next Mrs. Peterson barely an hour after he arrived on death row.
- This is often called "Bonnie and Clyde Syndrome", although they didn't have nearly as many fans as Hollywood might suggest, especially once they became known cop-killers. Some other criminals of the time period, like John Dillinger and Charles Arthur "Pretty Boy" Floyd, had far more.
- The "Free Jahar" (Dzhokhar Tsaranev, the younger Boston Marathon bomber) fangirly squeefest. Even Rolling Stone magazine got caught up in this one, running a controversial cover story that featured a profile of the young Tsaranev describing him as "a beautiful, tousle-haired boy with a gentle demeanor, soulful brown eyes and the kind of shy, laid-back manner that 'made him that dude you could always just vibe with,'" accompanied by a glamorous-looking cover shot.
- "Columbiners" are a subculture of people obsessed with the Columbine High School Massacre and its perpetrators, Eric Harris and Dylan Klebold. Many take it well beyond just an ordinary True Crime enthusiasm into idealizing "Reb and VoDKa" as heroes for disaffected youth, with three of them winding up implicated in a (thankfully thwarted) mass murder plot of their own in Halifax, Nova Scotia. Less thankfully, one Columbiner in Finland actually did manage to imitate his heroes and kill eight people at his school.
- Similarly, James Holmes, who shot up a movie theater in Aurora, Colorado during the premiere of The Dark Knight Rises, gained a following of "Holmies" afterwards.
- Likewise with the "Cruzers", fans of the Marjory Stoneman Douglas High School shooter Nikolas Cruz, who flooded the jail in Broward County, Florida with a deluge of fanmail and phone calls.
- Elliot Rodger, the Isla Vista shooter, has gotten a fanbase from the He-Man Woman Hater "incel" community.