Though criminological literature has paid attention to the use of informers in ordinary law enforcement, there is a research gap regarding their usage in contexts of conflict and political violence. This article explores the social, political and security functions of IRA informers in the transition from conflict in Northern Ireland. Based on that experience, it develops four heuristic models regarding informers that the paper argues may be of direct relevance to other conflicted and transitional societies. These are the informer as folk devil, the informer as rumour, the informer as political manipulator, and the informer as celebrity. All these themes demonstrate the long-term effects of the use of informers during the Northern Ireland conflict—an important finding given the increasing prevalence of the use of informers in a political context