The popular eighteenth-century genre of criminal biography is recognised today for its contribution to the development of the English novel, but its impact on Irish literature has not been explored to the same extent. However, criminal biographies were common fare for Irish readers in the 1700–1780 period. This chapter situates the criminal narrative, a form combining biographical and fictional content and drawing on the picaresque tradition, as an important subtext for the first Irish novels. It surveys the consumption of these texts in Ireland and their treatment of Irish settings and characters. Close readings are offered of a late-seventeenth-century fiction, The Irish Rogue (1690), and a mid-eighteenth-century collection of biographies, John Cosgrave’s A Genuine History of the Lives and Actions of the Most Notorious Irish Highwaymen, Tories and Rapparees (1747). Both can be singled out for their representations of nationality and travel, which enable them to undercut conventional associations between the Irish and criminality. Such rogue tales, it is argued, expanded the repertoire of Irish fiction, establishing characteristic strategies of plotting and characterisation which paved the way for later novels.