European ideas about unicorns spread across the world in the colonial era. In South Africa, hunts for that creature, and indigenous rock paintings of it, were commonplace. The aim was proof from ‘terra incognita’, often with the possibility of claiming a reward. There has, however, been little consideration of the independent, local creature onto which the unicorn was transposed. During cross-cultural engagements, foreign beliefs in the mythical unicorn and a desire for evidence of its natural history intermixed to an extraordinary degree with local beliefs in a one-horned animal. For over two centuries, colonists and researchers alike failed to realize that the local creature, by chance, resembled the European unicorn. A new synthesis of southern African ethnography, history and the writings of early travellers, missionaries and colonial politicians provides unambiguous evidence that one-horned creatures obtained in local beliefs before the arrival of colonists. Moreover, it shows that these creatures are depicted in South African rock art, and that they are a manifestation of San (Bushman) rain-animals. By ignoring relevant beliefs and images, previous scholars have failed to acknowledge that the South African unicorn was, apart from its four legs and single horn, a creature wholly different from the European one.