The enigmatic reserve heads of the Old Kingdom (2670-2168 BCE) in Egypt have been the topic of much discussion and debate since their discovery, primarily on the Giza Plateau, at the turn of the twentieth century. Their purpose and meaning to the ancient Egyptians confounded the first excavators who discovered them (de Morgan, Borchardt, Reisner, and Junker), and have puzzled the later Egyptian art historians, archaeologists, and Egyptologists who have studied them over the past century. This is mainly because the Egyptians did not leave a record for their use or function and because the heads were discovered in secondary context. All of the tombs in which they were found were either plundered or disturbed by flood, leaving them to much speculation. Their original discoverers and subsequent scholars have advanced numerous theories, which may or may not have a basis in the archaeological record. Included here is a closer examination of the form, typology, and archaeological context of the reserve heads, as well as an overview of the theories of their function and meaning, in short, an anatomy of an enigma.