Stereotypes have heiled from psychopathy, sociopathy, and schizophrenia, falling under the veil of a criminal label. They're portrayed in works of art as monsters, villains, and antagonists, when in real life, only the minority are killers of any type. Mentally ill people and people with personality disorders have been mistreated majorly by works of art as these specific tropes. And they're wrong.
Psycopathy. Hollywood brands these typically as serial killers that haunt the movie screens, when in real life, psychopaths are among us. They can work in high positions of power due to their charming charisma. Emotions don't play a role in their thoughts. While that can be scary to many, it's normal to them. It's a disorder, in which they can't understand what humans look for in emotional relationships. Goals are the main contender.
Sociopaths are also viewed as serial killers in Hollywood. While they are much like sociopaths, they are more impulsive and may not be able to hold a job as well as a psychopath would. In Confessions of a Sociopath by M.E. Thomas, she states, "I have never killed anyone, but I have certainly wanted to. I may have a disorder, but I am not crazy. In a world filled with gloomy, mediocre nothings populating a go-nowhere rat race, people are attracted to my exceptionalism like moths to a flame." Her book is a reliable outlet to the normal routine of a sociopath.
These two are mainly under the same umbrella. They both don't feel empathy, and have a toolbox of viewed immoral characteristics: lying, no boundaries, a lack of empathy. But not all of them act violently upon their violent thoughts. The minority of psychopaths and sociopaths perform violent crimes. Although they're more prone to it, it's a Hollywood cinema myth.
Schizophrenic people are also viewed as monsters from common misconcemptions. In fact, Cecilia McGough has a Ted Talk on which she discusses her life as someone with schizophrenia. She shares with the audience her hallucinations, one of the common ones being a scary clown like the one from It. She also reveals that as she speaks, the clown is in the audience, haunting her. This shocked many, but it also left them with pity suckerpunching their gut.
Although these mental illnesses and personality disorders have a higher rate of committing crimes, not all of them should be displayed as the common villain. They are real people living with something they cannot control. They are common people living an everyday life. More characters and explorations into the illnesses and disorders should be conducted for more representation. And especially, in murder mysteries, these specific illnesses and disorders can lead to sloppy writing in which the main killer's motives are because they were born that way.
But psychopaths, sociopaths, and schizophrenic people should be viewed deeper than the surface level of their disorder. They all have different experiences, relationships, routines, preferences. The main reason a stereotype stands is because nobody has broken it.
So let them be broken.