This article attempts to clarify the issue of the unreliable and/or untrustworthy narrator, a “textual device” likely to help us indirectly formalize the question of polyphony in literary fiction. We first present the metatheoretical position taken by proponents of the “rhetorical” approach (Booth), of structural narratology (Lintvelt, Jouve) and of cognitivism (Fludernik, Nünning), in order to clarify the criteria needed to establish the unreliability of the narrative voice. From a more critical perspective, we then mention several poetological typologies (Mercier and Fortier, Langevin) which help identify the textual variants of the “process” as well as its range of functions and effects. Through this discussion, we hope to shed light not only on the epistemological and aesthetical stakes and challenges of interpreting unreliable and/or untrustworthy narrators but also on polyphony in literary fiction.