Cluster B
A group of personality disorders marked by dramatic, emotional, or erratic behavior—including narcissism, borderline, antisocial, and histrionic types.
A diagnostic category in the DSM-5 comprising four personality disorders: narcissistic, borderline, antisocial, and histrionic. These conditions share patterns of emotional instability, impulsivity, and self-centered or attention-seeking behavior. The classification helps clinicians organize personality pathology, though individuals may exhibit traits across multiple clusters.
What this means in real life
A person with Cluster B traits might dominate conversations, react intensely to perceived slights, struggle with stable relationships, and prioritize their own needs—leaving friends exhausted and confused by unpredictable emotional swings.
What it isn’t
It is not a single diagnosis or a measure of how 'bad' someone is. Cluster B is a taxonomic grouping; someone may have traits from one or more disorders in the cluster, or none at all, and severity varies widely.
Commonly misused online
Social media often uses 'Cluster B' as shorthand for 'toxic person' or 'abuser,' flattening clinical distinctions and encouraging armchair diagnosis of public figures or exes without professional assessment.