The opening lines of Seneca's Thyestes (1–13), which feature Tantalus’ reference to the so-called great sinners, have received little critical attention. Through both an intertextual and an intratextual analysis, this article reveals the peculiarities of this allegedly canonical list of sinners by comparing it to similar catalogues in other Senecan dramas, as well as by identifying its structural function within this particular tragedy. This kind of two-fold approach enables a reinterpretation of certain key passages of the drama vis-à-vis lines 1–13, as well as a reassessment of Tantalus’ role as the creative force and architect of the tragedy.