This article explores the role of actors and agency in the literature on sustainability transitions. We reviewed 386 journal articles on transition management and sustainability transitions listed in Scopus from 1995 to 2014. We investigate the thesis that actors have been neglected in this literature in favor of more abstract system concepts. Results show that this thesis cannot be confirmed on a general level. Rather, we find a variety of different approaches, depending on the systemic level, for clustering actors and agency as niche, regime, and landscape actors; the societal realm; different levels of governance; and intermediaries. We also differentiate between supporting and opposing actors. We find that actor roles in transitions are erratic, since their roles can change over the course of time, and that actors can belong to different categories. We conclude by providing recommendations for a comprehensive typology of actors in sustainability transitions.