This introduction presents the project of literary invisibility studies. Beyond the currently dominant use of social invisibility as a metaphor of marginalisation, it synthesises two additional meanings of invisibility via a reading of Plato’s myth of the ring of Gyges. Hegemonic invisibility is the opposite of social invisibility: the power to act without surveillance and with impunity. Liminal invisibility denotes moments of agential potential when inhabiting invisibility. A theory of in/visible subjects defines the subject as emerging from the conflicting interplay of in/visibilisation and surveillance. I establish three major heuristic dimensions of the analysis of the content and form of invisible characters: power vs. powerlessness, realism vs. non-realism, and focalisation vs. voice. Historically, I trace the invisible character as a figure of the in/visible subject through five distinct stages, namely, eighteenth-century composition, Romantic configuration, late nineteenth-century dehumanisation, modernist diversification, and contemporary generalisation. The introduction demonstrates the significance of literary invisibility narratives for the theory of the subject and the history of cultural identities.