This article describes rhetorical innovations in late antique Christian polemic around the construction of orthodoxy/heresy and Christianity more broadly. Late antique Christian polemicists label groups as heretical by using their founders' names as eponymous proxies for an entire group and set of ideas: Marcionism/ites, Valentinianism/ites, and so forth. This type of group construction, which I term the polemic of individualized appellation due to the pejorative labeling of a group after an individual founder, is an intentional and often artificial type of elite, literary polemic put to service in the wider creative mythmaking and boundary/identity construction by heresiologists such as Justin, Irenaeus, Tertullian, Eusebius, and Epiphanius. In identifying both precursor ingredients in various ancient Mediterranean comparanda and novel developments in the Christian heresiologists' discourse, I also engage with recent scholarship on heresy, orthodoxy, and identity constructions in Late Antiquity. I explain why the polemic of individualized appellation was especially effective in constructing difference, its role in this particular late antique context, and its function in effacing apparent similarities in widespread practices and beliefs. I conclude with a methodological discussion, arguing that scholars in religion and history should reject their sources' categories of group identity construction due to their inherent bias.