Virgil has Evander trace the origins of the name of the river Tiber back to the death of a giant, called ‘Thybris’ (Aen. 8.330–2). This article argues that the reference to the violent (asper) giant can be understood as etymological wordplay on the Greek word hubris and as a potential allusion to the grammatical debate on the nature of aspiration. Varro's De gente populi Romani is identified as an important source for the characterization of the Tiber as a giant in primeval times. The political implications of the word hubris are also briefly explored with reference to various identities to which Evander alludes. The final part of the article argues that Theocritus’ Idyll 1 and the scholiast to Theocritus may have also inspired Virgil's description of the Tiber in this passage.