Working at the intersection of digital humanities, material text studies, media studies, and the history of the theater, this dissertation studies the transmedial exchange between the eighteenth-century theater and the novel. The theater and the novel were closely enmeshed in the eighteenth century: novels were adapted to the stage, plays were given a second life in prose, and numerous authors excelled in both forms. I argue that the century’s diverse theatrical mediascape—including forms such as actor portraits, scenery, costumes, puppet shows, playbills, and playtexts—shaped formal literary elements, from character to plotting, across both media forms. Rejecting the conventional theory of the novel that tracks its progress towards nineteenth-century realism, this project thus offers a picture of a far more experimental eighteenth-century novel, one deeply enmeshed in, and emerging from, its own contemporary mediascape.Chapter one argues that Eliza Haywood employs a theatrical mode of character in her novels, in which costuming and embodiment is fundamental to identity formation. This theatrical mode of character thus offers an alternative model of literary character to the model of psychological interiority so closely aligned with the novel form. Chapter two argues that Haywood’s Betsy Thoughtless (1751) and Henry Fielding’s Tom Jones (1749) should not be read as precursors to novelistic character development. Arguing that the novels’ narratives modes borrow from the newly emerging puppet theater, I show how narrative events in the novels do not become experiences and do not prompt character growth. Chapter three compares Burney’s novel Evelina (1778) to her play The Woman Hater, showing how Burney employs a theatrical mode of probability in Evelina’s plot. Only through this theatrical probability, I contend, can we understand the improbable accidents that fill Evelina. Chapter four studies the theatrical adaptation of novels, arguing that a new form of adaptation emerged at the end of the eighteenth century in tandem with innovations in scenography. I argue that this new form of immersive world-building adaptation, which recreates novels’ fictional worlds while often straying from their original plots, shaped how eighteenth-century audiences conceived of the novel as a media form.