Imagined others have been documented throughout the lifespan in relation to a range of developmental tasks. Although anecdotal evidence suggests that imaginary others are created in the context of athletic play in childhood and adolescence, they have never been studied systematically in this domain. Through retrospective surveys of 225 college students (38.8% men; Mage = 20.08, SD = 2.28; range 18–37 years), we investigated whether and how imaginary athletes were part of children's and adolescents’ repertoire, including the nature of their manifestations, links to their creators’ characteristics, and their functions. Imaginary athletes were reported by 40.9% of the sample, primarily men who remembered them from middle childhood; those with such creations rated themselves as having a greater predilection for fantasy. Patterns of imaginary athlete functions revealed three profiles: (a) minimally detailed utilitarian Placeholders that enabled play; (b) Athletic Tools, typically rivals with characteristics relevant to a sport; and (c) Social Relationships, imaginary athletes with detailed identities, typically manifesting as teammates. Descriptions of imaginary athletes included profile‐linked affordances relevant to middle childhood, suggesting that imaginary athletes might provide a mechanism for addressing developmental tasks of this period, such as mastery of skills and navigation of peer relationships.