Obsessive-compulsive disorder (OCD) is no longer classified as an anxiety disorder in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). It has become a flagship disorder of the new category of Obsessive Compulsive and Related Disorders (OCRDs) - a group of five disorders linked together by the core symptom of repetitive thoughts and behaviors and phenomenological and neurobiological similarity to OCD. Body dysmorphic disorder, hoarding disorder, trichotillomania, and skin picking disorder are the other disorders included in this group. In the upcoming eleventh edition of the International Classification of Diseases (ICD)-11, the World Health Organization (WHO) is planning to introduce similar changes to its own classification of OCD, further recommending the inclusion of olfactory reference disorder and hypochondriasis, in addition to the disorders listed in the DSM-5. In this article, we will review the classifications of OCD and OCDRs in the DSM-5 and the upcoming ICD-11, as well as describe the rationale and research leading to the creation of this new class of disorders.