In this article we develop a ‘hauntological’ reading of republicanism in postcolonial Ireland. This reading takes as its object the ways in which the politics of remembering–and remembering republican politics in particular–is equally a politics of time. Exploring the politics of republicanism through the lens of entangled temporalities, we develop an understanding of a particular mode of political desire. This republican political desire holds open the demand for a radical interrogation of the (post)colonial given. As such, it takes the form of a ‘dangerous memory’. Through the concept of a ‘dangerous memory’, we excavate a certain republican politics of refusal, that haunts the legitimacy and automatic reproduction of the postcolonial settlement and the attendant proprietary relations of inequality that it formalizes–culturally, politically, economically and legally. This theoretical interpretation of Irish republican hauntology is empirically explored through three historical layers and entangled temporalities that are organized around the ghosts of Roger Casement, a radical republican figure. The dangerous memories of Casement not only disrupt the canonical or official interpretation of Irish republicanism, but also open up the left-republican possibility to further interrogate the postcolonial present, both in Ireland and beyond.