Aceros is a genus of large south-east Asian hornbills (Bucerotidae family). This genus sometimes includes all species generally placed in the genus Rhyticeros. Alternatively, Aceros has been considered monotypic, only including the rufous-necked hornbill, in which case all of the remaining are moved to the Rhyticeros. Additionally, the white-crowned hornbill is sometimes placed in this genus, but most now place it in Berenicornis instead.