A lesser-known or lesser-discussed diagnosis is Aggressive-Sadistic Personality Disorder. This diagnosis helps conceptualize certain personalities with distinct features that don't fit neatly into other descriptions. Often, these individuals are mistaken for having narcissistic or antisocial personalities. Theodore Millon's conceptualization of Aggressive-Sadistic Personality is rooted in older ideas of sadism and masochism. Once explained, the features of this personality are easily recognized, especially by those who have lived with such individuals, as they are toxic both in the short term and particularly over time.

The diagnosis of Aggressive-Sadistic Personality is not currently included in the DSM psychiatric nomenclature. It was included at one time but later removed, much to the dismay of prominent psychologists. One reason for its removal was to prevent it from being used to justify bad behavior. While it falls under the broad category of personality disorders, it remains an extremely useful conceptualization for explaining many day-to-day and clinical situations.

Aggressive-Sadistic individuals are caustic, prone to putting others down, and abusive in personal relationships—whether overtly or subtly. They gravitate toward positions where they can oppress others. Toxic and domineering, they may seem stubborn and intransigent, but their primary goal is often to dominate. These individuals are characterized by dogmatic views, a lack of empathy, and hypersensitivity to interpersonal slights. Some are perpetual "put-down artists," though their methods may be covert. They may erupt explosively or convey their oppressive and domineering tendencies over time in subtler ways. Sometimes, they resemble a "shepherd dog," always pushing others in nearly indiscernible ways, much like a dog pressing against a leg while walking. Millon's writings describe this style in detail, and the term "Aggressive-Sadistic Personality" has gained traction on the internet, with many descriptions being largely accurate.

Understanding this personality type is particularly useful when working with individuals who have PTSD, as their trauma often stems from exposure to abusive people. A closer examination of many trauma histories reveals an aggressive-sadistic person lurking in the background. Emotional and physical abuse are the most common forms, but when these individuals engage in sexual abuse, it is typically power-based and domineering. A notable example is a well-known football coach who went to prison for years of abuse, demonstrating a domination-oriented pattern that extended across various areas of life. These individuals can be found in every walk of life and are often successful due to their forceful and imperturbable nature.

The term "narcissist" has become a common shorthand on social media for describing certain toxic traits, but it is often overused or inaccurately defined. Aggressive-sadistic personalities can be just as toxic, if not more so. They are often narcissistic as well and can create a positive impression in the outside world while being abusive at home. Despite their noxious traits, they deserve some pity, as they are trapped in their ignoble personality. Like the scorpion in Aesop's fable, they seem driven to hurt others gratuitously. Their abuse can be sudden or unfold over years, constantly creating difficult or impossible situations for those under their control. In positions of authority, they invariably inflict pain and damage. Though they may present as antisocial personalities or "sociopaths," they have distinct differences. Historical figures such as witch-hunters likely displayed aggressive-sadistic traits, thriving on righteous persecution.

This sadism often manifests in everyday scenarios: a teacher who believes punishment is good for children, a father who diminishes his child while praising others, or a boss who demeans workers publicly. These individuals often have a strong affinity for power symbols such as guns or aggressive imagery and enjoy war or crime movies that normalize recreational violence. Informally, they can be thought of as "punishment junkies." They may display aggressive toning in their clothing, own fierce animals or weaponry, and take righteous pleasure in the misfortunes of others. Some studies suggest that certain physical types—such as mesomorphic builds—might be more prone to this personality style, drawing comparisons to figures like drill sergeants or prison guards from popular media. With an aggressive-sadistic father, the most spirited child often becomes the primary target, correlating ADHD with PTSD due to over-punishment. These personalities justify their behavior by blaming their victims, and their victims' pain may incite further aggression.Their personality overlaps with other disorders, such as the rigidity of obsessive-compulsive personality or the paranoia of holding long-standing grudges. Their traits include bullying, narcissism, sadism, volatility, and paranoia.

If such individuals achieve positions of power, the effects can be devastating. On adolescent units, for instance, promoting a youth  in the peer hierarchy system with these features often leads to bullying and domination. They may ally with less aggressive peers who enjoy the proximity to power. The "good cop/bad cop" dynamic may originate from pairing an aggressive-sadistic individual with a more compliant and socially accepted counterpart.

Both men and women can exhibit aggressive-sadistic traits, which likely arise from a combination of genetics, life experiences, and nervous system characteristics. Some exhibit features akin to bipolar disorder, with a propensity for explosive outbursts. Living in fear of such outbursts often leads children to develop enlarged amygdalas and symptoms of chronic stress.

Aggressive-sadistic personalities are unlikely to find much satisfaction in old age. They often experience despair due to their inability to form meaningful friendships. 

One subtype, the "enforcing sadist," gravitates toward roles that allow them to control and punish others, such as military sergeants, university deans, or prison overseers. These individuals justify their actions as being for the greater good but are driven by deeper, more sinister motives. The more they dominate and punish, the more satisfaction and power they feel, often becoming intoxicated by their actions. Their socially sanctioned roles provide plausible deniability, leaving their victims feeling gaslit and powerless.

These individuals rarely change without significant effort. Even when they attempt a transformation, the result is often unstable, alternating between friendliness and aggression, perpetuating a cycle of instability.