Incels are defined as involuntary celibates who are part of an online community characterized by an anti-women ideology. We review research on the psychosocial characteristics of people identifying as Incels and compare their characteristics with general research on adult virginity and late sexual onset. Studies were identified through database search (Scopus, PubMed, PsycInfo and Google Scholar). Findings from 59 empirical studies were included. Incels are demographically, ethnically, and religiously diverse. Analyses of Incel forum discussions and survey responses report on psychological issues relating to negative body image, shyness, anxiety, social skill deficits, autism, bullying, sexual and romantic inexperience, loneliness, depression, and suicide. Research on adult virginity and late sexual onset report similar psychosocial characteristics and indicate feelings of being sexually "off time" relative to peers, but without a high prevalence of anti-women ideology. Future studies should focus on identifying why some sexually inexperienced adults participate in anti-women forums and identify as Incels, and if their mental health and psychosocial issues appeared before or after self-identifying as an Incel.