This chapter examines the phenomenon of three-county loyalists’ considerable impact on Northern Ireland’s security forces and radical or militant Ulster movements since partition. It describes how these individuals generally came from families that were threatened with, or experienced, republican or agrarian violence after partition. The chapter also explores the important roles played by three-county loyalists in paramilitary organisations such as the Ulster Defence Association during the Troubles. A number of these individuals came from areas that had seen high levels of loyalist militancy in the first half of the century, suggesting an intergenerational consistency across the twentieth century.