Marcus “the Magician” is described by Irenaeus of Lyon (Haer. 1.13–15 or 16) as a Valentinian teacher and leader of a community. Later sources are all dependent on Irenaeus; only Hipp. Haer. 6.39–54 offers some additional information on the Marcosians, probably based on oral sources and his own observations (Förster, 1999, 7–53, 153–158). It should be noted that Irenaeus’ report on Marcus and his followers does not extend beyond chapter…