This article surveys the contrasted views of twelfth-century chroniclers about Alexander the Great’s paternity. While some assumed the classical tradition that attributed it to Philip II, others affirmed that Alexander’s real father was the Egyptian magician Nectanebo, who had come to Macedon after running away from his country during the Persian conquest. He became a major historical figure in the medieval West thanks to the gradual spreading of the Latin versions of the Life of Alexander written by Pseudo Callisthenes. The analysis of the chronicles shows that this problem concerned mainly authors writing in the sphere of the Germanic Empire, for whom Alexander the Great’s empire was one of the emblematic steps of the translatio imperii. Nevertheless, the presence of the magician in these chronicles not only responds to questions of political theory; it should also be related to the growing interest among European intellectuals for the new knowledge and disciplines coming from the East, such as astronomy-astrology, alchemy and medicine, of which Nectanebo was a great expert.