Accessory bones are frequent anatomical variations of the skeletal system. They have a particularly high incidence around the foot and ankle. Supernumerary ossicles at the foot and ankle are often seen as incidental findings on radiographs taken for other purposes. Although they are mostly asymptomatic, they can be a source of pain or other pathologies. Knowledge of accessory bones is crucial to avoid misdiagnosis with protracted courses and even maltreatment. The differential diagnosis includes nonunions after fractures, loose bodies and osteophytes. In many cases, the exact etiology remains disputed, but there are certain signs for each bone on how to avoid diagnostic errors. The goal of this article is to summarize the current information about accessory bones of the foot, their prevalence, possible ontogenetic or phylogenetic origin, description, clinical consequences and treatment and options.