Homunculus is an extinct genus of New World monkey that lived in Patagonia during the Miocene. Two species are known: Homunculus patagonicus and Homunculus vizcainoi, which are known from material found in the Santa Cruz Formation in the far south of Argentina. H. patagonicus was a robustly built, quadrupedal primate, with body mass estimates varying between 1.4 and 5.9 kg based on different techniques. Some authors consider Killikaike blakei to be a junior synonym for H. patagonicus, but others consider the species distinct. While some studies have regarded Homunculus as a crown group platyrhine and a member of the family Pitheciidae, other studies have regarded it as a stem-group platyrhine outside any modern group, which is supported by the morphology of its nasal turbinates, which are dissimilar to those of crown-group platyrhines. Homunculus is suggested to have been primarily frugivorous based on dental wear.