The Parasites, or The Serial Killers, are the main antagonists of the 2012 indie horror game, The Cat Lady. They are five psychopathic serial killers who only live to cause pain and suffering to others, including Susan Ashworth .
- Xavier Zelmann/Doctor X: He is Liz's boss and the psychiatrist responsible for taking care of Susan during her time in the Cedar Lake Hospital. Though initially appearing to be a good-hearted and friendly man, Doctor X is actually a brutal serial killer who tortures and kills his patients; he also has twisted view on art, believing that pain and corpses are the only and true form of art. Liz mentions that he is an expert manipulator. Susan can either escape from him or kill him with a mace or a spear. Realistically, Doctor X's manipulative behavior and sadism imply that he suffers from Sadistic Personality Disorder, which makes him unable to feel any remorse for his actions and even enjoy torturing innocent people.
- Pest Control Man/The Pest Man: He is responsible for killing some of Susan's cats and kidnapping her. He eats not only cats, but is also a cannibal who kidnaps women for him to rape and eat. For unknown reasons, he likes to wear his gas mask while torturing his victims. He likes to collect guns and is a rather cowardly individual, not having enough courage to stop his wife from fatally harming the women he kidnaps. He is killed by Susan with Adam's poison. Realistically, his tendency to stay alone in his gun room, habit of wearing a gas mask, and indifference to Susan's pain imply that he suffers from Schzoid Personality Disorder and a very low IQ, which is supported by his slow-paced speech and the fact that he left a revolver for Susan to kill herself, despite knowing that she is restrained to a bed and permanently blinded after his wife poured bleach on her face.
- Gladys/Pest Control Man's Wife: Like her husband, she is a cannibal and the responsible for fatally torturing the women her husband kidnaps, it is also implied that she is the one who kills the women. Gladys is an extremely jealous person, she desfigures the women her husband kidnaps, as a way for him to not like them anymore. Gladys wears a nurse's costume, which could have been stolen from a previous victim. If compared to her husband, Gladys is far more cruel and evil. She is killed by Susan, who shoots her in the head with Pest Control Man's shotgun. Realistically, her impulsive and jealous nature imply that she suffers from Borderline Personality Disorder, which makes her think that her husband will fall in love with every women he kidnaps, leading her to desfigure them with strong bleach or even killing them.
- Carpenter/The Hangman: He is a mysterious and mute man who offers Susan a bouquet of flowers before bludgeoning her with a hammer. Though not confirmed, it is strongly implied that he was Susan's stalker and "secret admirer" who gave her a bouquet of flowers, which were responsible for the death of Susan's daughter, Zoe, who had a lethal and rare alergy to pollen. He attempts to hang Mitzi, but is mauled to death and eaten by Susan's cats. Realistically, if Carpenter is truly Susan's stalker, his constant need for approval and seductive behavior imply that he suffers from Histrionic Personality Disorder, which makes him continuously want Susan's attention, either by repeatedly calling her or giving her gifts, despite knowing that she was a mother and a married woman.
- Adam/The Eye of Adam: He is a paralyzed young man who spends his time trolling on the internet, under the username "The Eye of Adam". Adam is not only a troll, but also a serial killer who encourages depressed individuals to commit suicide, giving them his own recipe of hydrogen sulfide; one of his victims was Jack, Mitzi's boyfriend. When in danger, Adam is not afraid to kill his own father to stop Susan and Mitzi. Though paralyzed, Adam controls his keyboard via his left eye, hence his username. He also seems to have a genius-level intellect, being able to create complex traps and is a master of technology. Adam's fate is totally up to the player, he can be either killed by Susan and Mitzi or be left to die alone. Realistically, Adam's lack of empathy, sense of superiority, and the belief that he is a genuine "Preacher of Suicide" imply that he suffers from Narcissistic Personality Disorder, which is supported by the fact that Mitzi had to tell him that she admired his work in order for her to know where he lived.
- Every Parasite has a distinct connection to Susan:
- Doctor X was her psychiatrist.
- Pest Control Man and Gladys killed some of her cats.
- Carpenter could have been her "secret admirer".
- Adam was her neighbor.