Agency, in its many forms, has been identified as a driver of sustainability transitions. All the while, the role of agency vis-à-vis the circular economy (CE) transition remains poorly recognized. In this paper, we explore and conceptualize the agency driving the circular transition, acknowledging its diversity and therefore analyzing its different forms, ranging from individuals to organisations. Our research approach is abductive, building upon our interdisciplinary research team’s empirical research in five empirical case settings of CE transitions in the making in Finland, totalling 254 interviews and 56 meeting recordings, allowing us to explore diverse actor types enabling CE transitions. This leads us to develop a conceptualization of CE agency via a typology representing how actors at the individual, organisational, and meta-organisational levels of analysis exercise their active and relational agency in accelerating CE transitions. We argue that such active and relational agency, occurring across levels of analysis bears the potential to shift prevailing linear-economy-biased structures toward circularity. In closing, we argue that all actors have the potential to become CE catalysts, depending on the extent to which they recognize and exercise their CE agency.