Classical and medieval rhetorical theorists had many names for the figure of thought that we call ‘personification’ or prosopopoeia. This fundamentally hybrid figure occurs at the confluence of different kinds of discourse; definitions range across a spectrum from the ‘animate abstraction’ to the ‘person introduced to speak’. The essay explores the diverse rhetorical theory behind this figure. It then discusses the hybridity of this figure, and in particular its striking capacity for multivalency, change and even disintegration (paradiastole), in medieval vernacular narrative allegory. It focuses on Langland’s Piers Plowman, with reference to the figures Clergie, Patience, Conscience, Wil, Haukyn and Piers Plowman. Finally, the essay investigates another aspect of this hybridity that might seem counter-intuitive to readers who assume that prosopopoiae/personifications should have surface or even naturalistic narrative coherence: the way that this figure of thought allows Langland repeatedly to cultivate an ambiguity about whether his prosopopoiae/personifications are lay or ordained. This telling ambiguity reflects the poet’s disengaged attitude to the institution of the church and even the priesthood.