This thesis examines how British radical character was represented in the Romantic period. It takes as its starting-point two sets of changes in how character was understood at this time. In literary history, critics recognise that the late eighteenth and early nineteenth centuries were a time of transition for fictional characters: readers increasingly valued those who had an appearance of a deep interiority, over the more transparently-meaningful characters typical in the earlier eighteenth century. Similarly, in legal history, a shift was underway in how character evidence was used in criminal courts, from a focus on local reputation and social standing to more modern ideas about criminal responsibility. Scholars recognise that both changes were uneven, however, with older approaches to character persisting well into the nineteenth century. This thesis reads these two uneven transitions alongside each other, in the context of the period’s many political prosecutions. Beginning with the 1792 trial of Thomas Paine for Rights of Man and finishing with the 1824 trial of John Hunt for publishing Lord Byron’s Vision of Judgment, I consider how radicals defended their characters, inside and outside court. Examining the trials and writings of Paine, John Thelwall, William Godwin, Peter Finnerty, William Hone and Byron (the latter something of an outlier from this activist tradition), the thesis argues that readers and juries alike were expected to “read” character with increasing care. An address to an imagined reader, hostile or sympathetic, was embedded in radical self-defences, whether written specifically for a courtroom or not. Moreover, a high proportion of prosecuted radicals were writers or publishers, and their defences blur the boundaries between legal and non-legal registers. The thesis proposes that the legal meanings of character are an essential context for understanding how character was represented in a range of non-legal writings of the Romantic period