This article seeks to demonstrate that dramatically illustrated examples of the Celts’ sense of justice emerge as a minor trope in Greek and Roman ‘lighter literature’. In sources ranging from the Hellenistic to the Imperial era, novelistic narratives taking their cue from the register of lighter literature—with its emphasis on pathos, cultural difference, and romantic themes—feature several barbarian characters, characterised as ‘Celts’ or ‘Galatae’, who act according to a code of conduct that was constructed purposefully as barbarian, archaic, and alien. This set of motifs I venture to call the trope of ‘Celtic justice’. While almost certainly devoid of historical source value to actual judicial cultures of Iron Age Europeans, neither are these references mere alterité. Instead, their relationship with other literary registers demonstrate the literariness of certain modes of thought that came to inform the enquiry of Greek and Roman observers into the Celtic northerners. Their ostensibly ethnographical contents emerge as markers of complex textual strategies and vibrant reception of literary motifs. While lacking ‘anthropological’ source value, these texts demonstrate the variety and intensity with which the contacts between Greeks and Celts affected the epistemic regime of the Mediterranean societies.