A feeling of emptiness is commonly encountered in clinical practice, but it is poorly understood, with incongruent approaches to its definition and possible role in various disorders. This review examines the conceptualization of the feeling of emptiness and its place in psychopathology. We found an imbalance between theoretical approaches to this phenomenon and empirical research, and argue that more studies using adequate assessment tools are needed. Based on our literature review, we propose that a feeling of emptiness is a complex, negative emotional state that is experienced in different ways by different individuals. This feeling includes a physical or bodily component, a component of aloneness or social disconnectedness, and a component of a deep sense of personal unfulfillment or lack of purpose. The feeling of emptiness is related to other emotional states (dysphoria, boredom, loneliness, and numbness) and overlaps to some extent with them. Although the feeling of emptiness is most often considered in the context of borderline personality disorder, it is also encountered in depression, narcissistic personality disorder, and schizophrenia spectrum disorders, with its features potentially varying between different conditions. The feeling of emptiness may lead to nonsuicidal self-injury and may also have an important relationship with suicidality. We conclude by offering suggestions for further research, emphasizing a need to refine the multidimensional conceptualization of the feeling of emptiness and to better understand its manifestations and relationships with other emotions within various forms of psychopathology.