This study addresses the lack of critical analysis on Gregory of Nazianzus’ title of ‘the Theologian’. In doing so it addresses two areas: the origin of the title in the Address to Marcian, and the significance of its attribution to Gregory by Theodoret of Cyrrhus. Alongside Theodoret, this study takes account of a range of usages in Christian and non-Christian authors in order to argue that the title was attributed to Gregory as part of a pre-existing Christian response encompassing Moses, John and the prophets and pagan theologians such as Orpheus and Homer.